Foundations of Aromatherapy

About Ethers and Oxides Powerpoint Presentation

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About Ethers and Oxides

Are these components ethers or oxides? In essential oil chemistry, there’s significant confusion between these terms due to historical naming conventions that don’t align with precise chemical definitions. Most components called “oxides” in essential oil chemistry are technically ethers, specifically cyclic ethers – compounds where an oxygen atom is incorporated into a ring structure (C-O-C bonds within a ring). The term “oxide” in essential oil nomenclature is largely a historical convention rather than precise chemical terminology.

ETHERS

Ethers are organic compounds in which an oxygen atom connects two carbon atoms through single bonds (C-O-C). They can be either acyclic (open chain structure, R-O-R’) or cyclic (oxygen incorporated into a ring structure), and both types are commonly found in essential oils as volatile, aromatic components.

Ethers are organic compounds where an oxygen atom connects two carbon atoms (C-O-C):

• Acyclic ethers: Open chain structure (R-O-R’)
• Cyclic ethers: Oxygen incorporated into a ring structure (4, 5, 6+ membered rings)

Examples of CYCLIC ETHERS incorrectly called “oxides”:

• 1,8-Cineole (eucalyptol) – bicyclic ether, 6-membered ring with oxygen
• Rose oxide – cyclic ether with 6-membered ring with oxygen
• Linalool oxide – cyclic ether
• Sclareol oxide – Sclareol oxide contains a pyran ring (6-membered cyclic ether)

OXIDES

In organic chemistry, true oxides include epoxides (3-membered rings containing one oxygen atom) and peroxides (compounds containing an oxygen-oxygen bond, R-O-O-R), both of which are significantly more reactive than larger cyclic ethers due to ring strain or bond instability.

True Organic Oxides include:

• Epoxides: 3-membered rings containing one oxygen (also called oxiranes), e.g. b-caryophyllene oxide
• Peroxides: Contain an oxygen-oxygen bond (R-O-O-R)

Examples of TRUE OXIDES:

• β-caryophyllene oxide – contains an epoxide ring (3-membered)
• Ascaridole – contains a peroxide bridge (O-O bond)

Key Distinction:

Epoxides (3-membered rings) are chemically oxides. Larger cyclic ethers are just ethers, despite often being called “oxides” in essential oil nomenclature. Both can appear in essential oils, have similar volatility, and contribute to aroma, but their chemical classification is different.

Food for thought:

The term “oxide” commonly used in aromatherapy literature to describe compounds like β-caryophyllene oxide, linalool oxide, and bisabolol oxides likely stems from the practical observation that these molecules are oxidation products of their parent terpenes, rather than from strict chemical nomenclature. When essential oil components containing carbon-carbon double bonds are exposed to atmospheric oxygen—either naturally in the plant or post-distillation during storage—oxygen atoms are added to these vulnerable sites, frequently forming cyclic ethers or epoxide or peroxide (true oxide) components.

Ethers/oxides compounds have names which end in -oxide or
in the case of eucalyptol -ol.

Ether & Oxide Physical Characteristics

• Polarity: Both are moderately polar (less than alcohols, more than hydrocarbons)
• Solubility: very slightly soluble in water, soluble in non-polar solvents such as vegetable oils
• Volatility: ethers are highly volatile; oxides are volatile depending on structure
• Boiling point: lower boiling point than alcohols of similar structure
• Aroma: variable aroma strength, giving characteristic aromas to the essential oils in which they occur, even at percentages as low as 0.3% (for example, rose oxide in Rosa damascena oil)
• Color: colorless

Examples of Ethers and True Oxides

NOTE: The ethers are a unique chemical family in that it is hard to generalize about the whole family. The main ether component found in essential oils is eucalyptol. Most of the other oxides are found as minor components of essential oil, generally at less than 1 to 3%, with the exception being the bisabolols, which can occur as major components of German chamomile essential oil. We will focus our attention on eucalyptol in the sections that follow.

General therapeutic actions of eucalyptol:

• • Analgesic
  • Anti-inflammatory
  • Antiviral (respiratory)
  • Antibacterial (respiratory)
  • Powerful Expectorant
  • Decongestant (respiratory)
  • Mucolytic
  • Immunomodulatory

• Preventative to respiratory disorders
• Supportive to the respiratory system

Eucalyptol-rich essential oils

1,8 cineole rich essential oils:

• Eucalyptus radiata: 65-75%
• Eucalyptus globulus: 72.71-85.82%
• Eucalyptus polybractea: 60-95%
• Eucalyptus dives: 60-75%
• Eucalyptus smitthi: 70-80%
• Laurel (Laurus nobilis): 31.9-58.59%
• Myrtle ct cineole (Myrtus communis): 50+%
• Niaouli ct. cineole (Melaleuca quinquenervia): 49-62%
• Ravintsara ct. cineole (Cinnamomum camphora): 50-68%+
• Rosemary ct. cineole (Salvia rosmarinus): 19-37+%

Safety notes for eucalyptol-rich essential oils

• Ether components are relatively non-toxic when used appropriately.
• Keep eucalyptol-rich essential oils away from infants and children. Numerous case reports reveal the high incidence of children unintentionally taking eucalyptol-rich essential oils internally. Adverse reactions may include epigastric pain, vomiting and CNS symptoms, burning sensation in the mouth and throat, spontaneous vomiting, respiratory difficulty, and seizures.^3,4
• Avoid applying eucalyptol-rich essential oils to the face or nose of infants or young children (under age 5). Do not instill in nose of infants or young children (e.g. via nasal spray).
• Do not use eucalyptol-rich essential oils orally with children under three.

About Phenols Powerpoint Presentation

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About Phenols

Phenols are organic components that contain a hydroxyl group (-OH) directly attached to the carbon of a benzene ring. The –OH group attachment to the benzene ring (it’s cyclic structure and placement of double bonds) makes this bond quite powerful. Phenols can be highly reactive, potentially creating more irritating components. All phenols exhibit antimicrobial activity.¹

The names of phenol compounds, like alcohols, end in –ol.
Since there are fewer phenol compounds and to avoid confusion with alcohols, it is recommended that students memorize the name of phenols commonly found within essential oils.

Reactivity of Phenols Explained

The benzene ring becomes much more reactive when it has an -OH group attached because of something called “electron sharing.” Here’s the simple explanation:

The oxygen atom in the -OH group has extra electrons that it can share with the benzene ring. Think of it like the oxygen is “lending” some of its electrons to the ring system. This sharing makes the whole molecule more stable after it gives up its hydrogen atom to neutralize free radicals.

When a phenol donates its hydrogen to stop a harmful free radical, the remaining molecule (now missing that hydrogen) doesn’t fall apart because the oxygen’s electrons and the ring’s electrons work together to keep everything stable. This teamwork between the oxygen and the benzene ring is why phenols are such effective antioxidants – they can easily give up their hydrogen to help, and then remain stable afterward.

Regular alcohols (without the benzene ring) can’t do this electron-sharing trick, which is why phenols are much more powerful antioxidants than simple alcohols.

Physical characteristics of phenols:

Polarity: polar molecules (due to the polar hydroxyl group)
Solubility: slightly more soluble in water than alcohols
Volatility: slow to evaporate
Boiling point: higher boiling points than alcohols
Aroma: very potent aroma with a pungent quality
Color: colorless to light yellow

Phenols found in essential oils

• carvacrol: Oregano species, Thyme species, Winter savory
• thymol: Thyme
• eugenol*: Clove bud

Eugenol Insight

Eugenol is both a phenol and a phenylpropanoid. As you can see from its visual structure, eugenol contains both the hydroxyl group (-OH) directly attached to the carbon of a benzene ring (phenol) and a basic 3-carbon chain (tail) attached to a benzene ring (phenylpropanoid). It is typically classified as a phenylpropanoid (eugenol is covered in the next lesson).

General therapeutic actions of phenols

• Powerful anti-infectious
• Broad spectrum: antibacterial, antiviral, antifungal, and antiparasitic
• Potent antibacterial and antifungal treatments of the respiratory and digestive systems
• Analgesic (clove, cinnamon leaf)
• Antioxidant
• Warming, stimulating
• Supports and enhances immune system

Core therapeutic indications for phenol-rich essential oils:

• bacterial, viral or fungal infections
• parasitic infections

Phenol-rich essential oils

• Thyme ct. thymol (Thymus vulgaris): thymol (30-50%)
• Oregano (Origanum vulgare): carvacrol (55+%)
• Turkish oregano (Origanum onites): carvacrol (25%+), thymol (14-17+%)
• Winter savory (Satureja montana): carvacrol (30.16-63.4%), thymol (0.61-14.1%)
• Monarda (Monarda fistulosa): thymol (55+%)
• Monarda (Monarda didyma): thymol (55+%)
• Ajowan (Trachyspermum ammi): thymol (35-87.75%) and carvacrol (11.17%)
• Oregano (Origanum compactum): carvacrol (30.53-43.97%) and thymol (11.56-27.5%)

Safety for phenol-rich essential oils

• Phenol compounds can be dermacaustic if used undiluted and may cause a burning sensation or irritation when in contact with mucous membranes or the skin. Essential oils rich in phenols should always be diluted prior to use. The highest recommended dilution for phenol-rich essential oils for the cutaneous route is 10-20% for a localized application.
• Phenol components are potential hepatotoxins if administered at high doses over long periods (> 3 months, 1 gram / day).
• It is recommended to keep internal use to a maximum of 6-15 days. Phenol-rich essential oils are typically employed for their anti-infectious and antimicrobial activity during the acute phase of illness. However, phenols may be used for chronic conditions with low doses over prolonged periods (12 months) when formulated with hepatoprotective essential oil (see next point).
• When using phenol-rich essential oils internally, it is recommended to use a hepatoprotective essential oil, such as lemon (Citrus limon), Carrot (Daucus carota) or rosemary ct verbenone (Rosmarinus officinalis), in the formulation.
• Avoid the use of phenol-rich essential oils with individuals with liver disease.

Safety for specific components

• Thymol: The oral use of essential oils rich in thymol is contraindicated for individuals who are on anticoagulant drugs, are about to have major surgery, or have a peptic ulcer. Thymol is also contraindicated during childbirth and for people who have hemophilia or other bleeding disorders. High doses and prolonged use of thymol-rich essential oils may contribute to hepatotoxicity.
• Carvacrol: Avoid oral use of carvacrol-rich essential oils with individuals who are on medication to control blood glucose.

About Phenylpropanoid Powerpoint Presentation

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About Phenylpropanoids

Phenylpropanoids contribute to all aspects of plant responses towards biotic and abiotic stimuli, by providing building units of physical barriers against pathogen invasion, by synthesizing an array of antibiotic compounds, and by producing signals implicated in the mounting of plant resistance.¹

Phenylpropanoids are the simplest of the shikimic-acid-derived components. They consist of a basic 3-carbon chain (tail) attached to a benzene ring.² Recall from the phenol lesson, the presence of the benzene ring (it’s cyclic structure and placement of double bonds) makes this bond quite powerful.

Phenylpropanoid compounds have names which end in –ole or -ol.
(exception is cinnamic aldehyde)

Physical characteristics of phenylpropanoids

Polarity: slightly polar
Solubility: very slightly soluble in water, soluble in ethanol
Volatility: more volatile then sesquiterpene-lactones and furanocoumarins
Boiling point: lower boiling points then sesquiterpene-lactones and furanocoumarins
Aroma: powerful aroma, very potent aroma with a pungent, slightly sweet quality
Color: clear to yellow/brown

Phenylpropanoids found in essential oils

• cis-anethole (Z-anethole): anise (up to 2.5%)
• trans-anethole (E-anethole): anise (up to 80%), Fennel (up to 90%)
• methyl chavicol syn. estragole: basil, fennel, tarragon
• safrole: camphor, sassafrass
• cinnamaldehyde: cinnamon bark
• eugenol: clove, basil species
• methyl eugenol: Laurel (≤9%), Myrtle (≤1%), Ravinsara (≤1%), Clary sage (≤2%), Melissa (1%)³

General therapeutic actions of phenylpropanoids:

• Airborne antimicrobials
• Antimicrobial
• Antifungal
• Anti-inflammatory
• Antispasmodic
• Stress-modulating⁴
• Digestive⁵

Core therapeutic indications for phenylpropanoid-rich essential oils:

• bacterial, viral or fungal infections
• parasitic infections
• affinity for the digestive and respiratory systems
• antispasmodics

Phenylpropanoid-rich essential oils

• Anise (Pimpinella anisum)
• Clove bud (Eugenia caryophyllata)
• Basil ct. methyl eugenol (Ocimum basilicum)
• Basil ct. methyl chavicol (Ocimum basilicum)
• Holy basil (Ocimum sanctum)
• Fennel, Sweet (Foeniculum vulgare var. dulce)
• Star anise (Illicium verum)

Safety for phenylpropanoid-rich essential oils

Essential oils rich in any of the three components listed below should be used with caution in oral doses by diabetics taking drugs to control blood glucose. Oral dosing is also cautioned in conjunction with anticoagulant drugs, major surgery, childbirth, peptic ulcer, hemophilia and other bleeding disorders.⁶ Trans-anethole exhibits antiplatelet aggregation activity.⁷

• Methyl chavicol
• Cinnamic aldehyde
• Eugenol
• Trans-anethole

• Eugenol: Essential oils rich in eugenol should be used with caution in oral doses by anyone taking antidepressants, including monoamine oxidase inhibitors (MAOIs), Selective serotonin reuptake inhibitors (SSRIs); or opioid pain medication, pethidine, and indirect sympathomimetics. Eugenol is a mild dermal irritant.⁸

• Trans-anethole: Trans-anethole has exhibited estrogenic actions and therefore essential oils containing significant quantities (e.g. >15%) of trans-anethole should be avoided via any route during pregnancy, while breastfeeding, or if client is diagnosed with endometriosis or an estrogen dependent cancer.⁹

About Aldehydes Powerpoint Presentation

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About Aldehydes

Aldehydes are components that contain the functional group called: the carbonyl group (C=O). The carbonyl group consists of one carbon atom double-bonded to one oxygen atom.

Aldehydes are components that have the carbonyl group directly terminally attached to a carbon atom and at least one hydrogen atom. It is this single hydrogen atom that differentiates an aldehyde (left image) from a ketone (right image).

Another point of differentiation between aldehydes and ketones is that with aldehydes the carbonyl group is found at the end of the carbon chain whereas ketones have the carbonyl group inside the chain or directly on the ring.¹

Aldehydes are polar compounds. The presence of the carbonyl group, which is a quite polar functional group, makes the component somewhat more water-soluble then it would be without it.²

Aldehyde compounds have names which end in –al.

Physical characteristics of aldehydes:

Polarity: polar molecules
Solubility: slightly less soluble in water than alcohols of a similar size
Volatility: readily oxidize into carboxylic acids, thus exhibiting more irritating effects
Boiling point: lower boiling point than alcohols yet a higher boiling point than hydrocarbon molecules
Aroma: some of the most aromatic molecules within essential oils and have a slightly fruity aroma when smelled as isolated chemicals
Color: colorless

Aldehydes found in essential oils:

• citronellal: citronella, Eucalyptus citriodora, melissa
• citral: lemongrass, lemon verbena
• geranial: lemongrass, melissa, Litsea cubeba, lemon myrtle
• neral: lemongrass, melissa, Litsea cubeba, lemon myrtle

General therapeutic actions of aldehydes:

• Antibacterial
• Antifungal
• Anti-inflammatory
• Antiviral
• Anxiolytic
• Hypotensive
• Calming and sedative
• Stimulants of the digestive and hepatic functions
• Potential skin irritants

Core therapeutic indications for aldehyde-rich essential oils:

• Rheumatic disorders (e.g. rheumatoid arthritis, carpal tunnel syndrome, fibromyalgia, etc.)
• Tendinous pathologies (e.g. tendinitis)
• Nervous system (e.g. anxiety, stress)

Aldehyde-rich essential oils

• Citronella (Cymbopogon nardus)
• Lemon Eucalyptus (Eucalyptus citriodora)
• Lemongrass (Cymbopogon citratus)
• Melissa (Melissa officinalis)
• May chang (Litsea cubeba)
• Lemon myrtle (Backhousia citriodora)

Safety notes for aldehyde-rich essential oils

• Aldehydes are irritating to the skin and mucous membranes. Because of this, it is important to always dilute aldehyde-rich essential oils into a vegetable/herbal oil or other base prior to applying to the skin.
• Citral may cause skin sensitization at doses above 0.5%. Essential oils rich in limonene, specifically grapefruit or lemon, may be used in the formulation to quench (prevent) the sensitizing potential of citral.
• Maximum dilution recommend for aldehyde-rich essential oils is 50% for adults, 20% in adults with hypersensitive skin and 10% for young children.

About Ketones Powerpoint Presentation

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About Ketones

Ketones are similar to aldehydes with the exception that only carbon atoms are directly attached to either side of the carbonyl group (C=O).

Physical characteristics:

• Polarity: moderately polar compounds
• Solubility: slightly less soluble in water than alcohols
• Volatility: stable and not prone to oxidation
• Boiling point: a lower boiling point than alcohols yet a higher boiling point than hydrocarbon molecules
• Aroma: fruity or musty notes, can be very powerful even in very small amounts (e.g. nookatone)
• Color: generally clear

Ketone compounds have names which end in –one, except for camphor.

Examples of common ketones found in essential oils
camphor, menthone, thujone
d-carvone, pulegone, piperitone,
l-carvone, verbenone, pulegone
fenchone, cryptone, nootkatone
pinocamphone, italidiones, valeranone

General therapeutic actions of ketones:

• Mucolytics
• Promote skin/tissue regeneration (specifically, Rosemary ct. verbenone)
• Wound healing agents
• Anti-infectious
• Some ketone components have the potential to be neurotoxic or hepatotoxic when used internally, in high dosages or over a long period of time: use care and knowledge with application

Ketone-rich essential oils

• Turmeric (Curcuma longa) – ar-turmerone (55%+)
• Caraway (Carum carvi) – carvone (>37.98%)
• Dill (Anethum graveolens) – carvone (>35%)
• Spearmint (Mentha spicata) – carvone (41-73%)
• Fennel (Foeniculum vulgare) – fenchone (6-12%)
• Pennyroyal (Mentha pulegium) – menthone (3-19%)
• Peppermint (Mentha x piperita) – menthone (14-32%)
• Pennyroyal (Mentha pulegium) – piperitenone (16-21%)
• Rosemary ct. verbenone (Rosmarinus officinalis) – verbenone (10-18+%)

Ketone-rich essential oils with safety concerns for specific component

Camphor

• Rosemary ct. camphor (Rosmarinus officinalis) – camphor (>17%- upwards of 37+%)
• Spanish sage (Salvia lavandulifolia) – camphor (27-29%)
• Sage (Salvia officinalis) – camphor (18-24%)

Pinocamphone

• Hyssop ct. pinocamphone (Hyssopus officinalis) – pinocamphone (upwards of 49%)

Pulegone

• Spearmint ct. pulegone (Mentha spicata) – pulegone (>50%)

Safety notes for ketone-rich essential oils

• There are specific ketones (listed above) which are considered neurotoxins in high dosages or when take over a long period of time.
• The toxicity of ketones varies with the route of administration (potential toxicity is greater when given via the oral route and lower when given via the cutaneous route), the dilution/dosage used, the place of application on the body, and the type of ketone.
• It is best to completely avoid the use of camphor, pinocamphone, or pulegone-rich essential oils with individuals who are pregnant and/or lactating, children under 7 years. Also avoid internal use with individual diagnosed with epilepsy as well as with the elderly.

Essential oils containing ketones that have safety concerns

Rue (Ruta graveolens)
May be abortifacient, phototoxic (moderate risk); may be photocarcinogenic. It is contraindicated during pregnancy and breastfeeding.

Mugwort (Artemisia vulgaris)
Mild neurotoxin, based on thujone content. Contraindicated via all routes (internal, external, inhalation) during pregnancy and breastfeeding.

Wormwood (Artemisia absinthium)
Rich in b-thujone. Considered to be neurotoxic, embryo-fetotoxicity, and abortifacient. Contraindicated via all routes (internal, external, inhalation) during pregnancy and breastfeeding.

Thuja (Thuja occidentalis)
Rich in a-thujone and fenchone. Considered to be a neurotoxin. Should not be used internally at all. Contraindicated via all routes (internal, external, inhalation) during pregnancy and breastfeeding.

Pennyroyal (Mentha pulegium)
Rich in (1R)-(+)-b-pulegone and menthone. Considered to be hepatotoxic and neurotoxic. Should not be used internally. Contraindicated via all routes (internal, external, inhalation) during pregnancy and breastfeeding.

Sage (Salvia officinalis)
Rich in camphor and/or a-thujone. Considered to be a neurotoxin. Should not be taken orally. Contraindicated via all routes (internal, external, inhalation) during pregnancy and breastfeeding.
All safety information from: Tisserand and Young (2013).

About Monoterpene Alcohols Powerpoint Presentation

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About Monoterpene Alcohols

Monoterpene alcohols are organic compounds that contain a hydroxyl group (-OH) attached to one of the carbon atoms of the monoterpene chain.

An example of the -OH group (hydroxyl group) is the common molecule linalool:

Monoterpene alcohol components have names that end in –ol.

Physical characteristics of monoterpenols:

Polarity: very polar molecules
Solubility: slightly soluble in water
Volatility: less volatile then monoterpenes, oxidize slower than monoterpenes
Boiling point: higher boiling points than monoterpenes
Aroma: pleasant aromas, sweet
Color: colorless

Examples of common monoterpenols found in essential oils

borneol, lavandulol
nerol, citronellol
linalool, terpinen-4-ol
geraniol, menthol
α-terpineol

General therapeutic actions of monoterpene alcohols:

• Antimicrobial (broad-spectrum: antibacterial, antifungal, antiviral)
• Anti-infectious
• Anti-inflammatory
• Mild and well tolerated by the skin
• Antispasmodic
• Nervine
• Immune modulators, preventative to disease**
  **By soothing the nervous system, reducing stress, and nurturing the individual.

Core therapeutic indications for monoterpene alcohol-rich essential oils:

• Viral, bacterial, fungal infections
• Nervous system: anxiety, stress related conditions, etc.
• Wide range of activity depending on individual essential oil

Safety for monoterpene alcohol-rich essential oils

• This family is very used in aromatherapy and very important because of the general lack of toxicity in therapeutic doses.
• Menthol should not be applied to large areas of skin.
• Toxicity: none at physiological doses- good cutaneous and oral tolerance.
• When exposed to the air, primary monoterpenols slowly oxidize to aldehydes and acids, or form resins, which means that essential oils containing them should also be stored away from air, light, and heat.¹

Monoterpene alcohol-rich essential oils

• Bergamot (Citrus bergamia): cold pressed or distilled
• Citronella, Ceylon (Cymbopogon nardus)
• Clary sage (Salvia sclarea)
• Coriander seed (Coriandrum sativum)
• Geranium (Pelargonium asperum)
• Lavender (Lavandula officinalis)
• Lavendin (Lavandula x intermedia)
• Melissa (Melissa officinalis)
• Neroli (Citrus aurantium var. amara flos.)
• Palmarosa (Cymbopogon martini)
• Petitgrain (Citrus aurantium var amara – leaf)
• Rose (Rosa damascena) essential oil
• Thyme ct. geraniol (Thymus vulgaris)
• Ylang ylang #1 (Cananga odorata forma genuina)

About Sesquiterpene Alcohols Powerpoint Presentation

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About Sesquiterpene Alcohols

Sesquiterpene alcohols are organic compounds that contain a hydroxyl group (-OH) attached to one of the carbon atoms of the sesquiterpene chain. Sesquiterpenols typically contain at least one closed ring structure.

Oils such as Pogostemon cablin (patchouli) and Santalum album (sandalwood) produce characteristic sesquiterpenols: patchoulol and the santalols.¹ Sesquiterpene alcohols tonify the muscles and nerves, reduce congestion in the veins as well as in the lymphatic system and have moderate antimicrobial activity.²

Alcohol compounds have names that end in –ol.

Examples of common sesquiterpene alcohols found in essential oils

α-bisabolol, daucol, α-santalol
carotol, farnesol, β-santalol
cedrol, patchoulol, zingiberol

General therapeutic actions of sesquiterpene alcohols:

• Anti-inflammatory
• Antimicrobial
• Antimycotic
• Calming and soothing (nervous system, endocrine system and emotions)
• Most have strong affinity with the skin
• Venous and lymphatic decongestants
• tonic and general stimulants
• Sclareol: estrogen-like activity (French model)

Core therapeutic indications for sesquiterpenol-rich essential oils:

• acute or chronic inflammation
• minor bacterial, viral or fungal infections
• inflamed skin conditions
• wound healing / vulnerary
• Nervous system, psyche/emotion: anxiety, stress, feelings of being overwhelmed, etc.

Sesquiterpenol-rich essential oils

• German chamomile (Matricaria recutita)
• Carrot seed (Daucus carota)
• Cedarwood (Juniperus virginiana)
• Clary sage (Salvia sclarea)
• Patchouli (Pogostemon cablin syn. P. patchouli)
• Sandalwood (Santalum album)
  ________________________________________________________________

Safety notes for sesquiterpenol-rich essential oils

• Sesquiterpenols (Sesquiterpene alcohols) are generally non-toxic and safe to use via all routes.

Introduction to Terpenes

Terpenes and terpenoids are the most abundant and structurally diverse group of plant secondary metabolites. There are over 22,000 known terpene compounds. They play an important role in plant-insect, plant-pathogen, and plant-plant interactions.

Essential oils contain simple hydrocarbons in the form of terpenes and more complex terpenoids called oxygenated hydrocarbons, or substituted hydrocarbons, in the form of alcohols, phenols, phenylpropanoids, esters, aldehydes, ketones, oxides, sesquiterpene lactones, and furanocoumarins.

The term terpene usually refers to a hydrocarbon molecule (e.g. monoterpenes and sesquiterpenes) while terpenoid refers to a terpene that has been modified, such as by the addition of oxygen (e.g. alcohols, esters, ketones, etc.). The simplest organic compounds and the basic backbone of essential oils are hydrocarbons, consisting solely of hydrogen and carbon.

Terpenes are classified according to the number of isoprene units (see Figure 4.1) that their molecules contain. All terpenes and terpenoids are derived by repetitive fusion of branched five-carbon units based on the isopentane skeleton. The isoprene unit is also sometimes referred to as methylbuta-1, 3-diene, and is the molecular structural unit from which unsaturated hydrocarbons are derived. Each isoprene unit contains 5 carbon atoms.

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About Monoterpenes

The simplest organic compounds and the basic backbone of essential oils are hydrocarbons, compounds consisting solely of hydrogen and carbon. Essential oils contain simple hydrocarbons in the form of monoterpenes and sesquiterpenes.

Monoterpenes are unsaturated* hydrocarbons formed by the joining of two isoprene units. Since each isoprene unit has five carbon atoms, a monoterpene has ten carbon atoms. The molecular formula for monoterpenes is: C10H16.

*unsaturated: each monoterpene component contains at least one double bond

In the diagram below the pink circles represent the 10 carbon atoms and the orange circles represent the 16 hydrogen atoms. *Remember, each carbon atom can bond with up to four additional atoms, including other carbon atoms.

Physical characteristics of monoterpenes:

• Polarity: non-polar compounds
• Solubility: insoluble in water (hydrophobic), soluble in non-polar solvents such as vegetable oils
• Volatility: highly volatile, prone to oxidation
• Boiling point: low boiling points, monoterpenes boil between 140°C and 180°C. This makes them volatile, meaning they evaporate easily and create the smells we notice.
• Aroma: some monoterpenes have a characteristic aroma, while others have little to no aroma e.g., alpha-pinene has a sharp, piney aroma reminiscent of pine, while d-limonene possesses a light and sweet citrusy odor with a strong resemblance to sweet orange, and camphene imparts a turpentine, camphoraceous aroma.
• Color: colorless

Monoterpenes have names that end in -ene.

Examples of common monoterpenes found in essential oils

General therapeutic actions of monoterpenes:

• Air antimicrobials and air purifiers
• Antimicrobial, antiviral
• Antioxidant
• Dermal penetration enhancers (highly lipophilic)
• Drying/dehydrating effect on skin and mucous membranes
• Stimulating / Energizing / Uplifting
• Analgesic (e.g., pinenes)
• Refreshing/uplifting
• Respiratory decongestants (drying)
• Balsamic expectorant (anti-inflammatory)
• Cortisone-like (the pinenes, French aromatic medicine)
• Muscle decongestants (improve circulation and reduce stagnation)

Core therapeutic indications for monoterpene-rich essential oils:

• Respiratory pathologies, particularly when excess mucous is present (bronchitis, flu, coughs and colds, etc.)
• Congestive diseases of the venous system and lymphatic
• Nervous system: anxiety, depression, stress-related conditions, stress, etc.
• Musculoskeletal system: Helps with general pain and muscle spasms, which are relieved by the rubefacient effect. *Citrus fruits and black pepper.

Essential oils rich in monoterpenes include:

• Angelica root (Angelica archangelica)
• Bergamot (Citrus bergamia) cold pressed and distilled
• Black pepper (Piper nigrum)
• Black spruce (Picea mariana)
• Fir, Balsam (Abies balsamea)
• Frankincense (Boswellia frereana)
• Grapefruit (Citrus paradisi)
• Hemlock (Tsuga canadensis)
• Juniper berry (Juniperus communis)
• Lemon (Citrus limon)
• Mandarin (Citrus reticulata)
• Sweet orange (Citrus sinensis)
• Pine, Scots (Pinus sylvestris)

Safety notes for monoterpene-rich essential oils

• Monoterpenes react easily to oxygen and can degrade quickly (particularly citrus and pine essential oils rich). This degradation can make monoterpene-rich essential oils potential skin irritants or sensitizers. To avoid oxidation, it is important to store essential oils correctly and to ensure that the essential oil being used has not degraded to a point where it is no longer useful in therapy and may cause irritation or sensitization responses.
• Essential oils rich in monoterpenes are best stored in the refrigerator or somewhere of similar cool temperatures.
• We recommend a maximum dilution of 50% for monoterpene-rich essential oils for dermal application.

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About Sesquiterpenes

Sesquiterpenes, like monoterpenes, are simple hydrocarbons. Sesquiterpenes have 15 carbon atoms however, and are based upon the joining of three isoprene units. The molecular formula for sesquiterpenes is: C15H24. (The green circles below represent the carbon atoms.)

Physical characteristics of sesquiterpenes:

• Polarity: non-polar compounds
• Solubility: insoluble in water (hydrophobic), soluble in non-polar solvents such as vegetable oils
• Volatility: less volatile then monoterpenes, oxidize slower than monoterpenes
• Boiling point: higher boiling points than monoterpenes
• Aroma: more aromatic then monoterpenes,
• Color: colorless, except for chamazulene

Sesquiterpenes have names which end in –ene.

Examples of common sesquiterpenes found in essential oils

bisabolene, chamazulene (only 14 carbon atoms), guaiazulene
α-vetivene, aromadendrene, α-cedrene
Germacrene D, α-ylangene, β-cadinene
ar-curcumene, α-humulene, β-selinene
α-caryophyllene, β-elemene, β-sesquiphellandrene
zingiberene, β-caryophyllene, α-farnesene, β-santalene

General therapeutic actions of sesquiterpenes are:

• Powerful anti-inflammatory
• Antispasmodic
• Moderate antimicrobials
• Calming and soothing to the nervous system
• Sedative
• Hypotensive
• Decongestant venous and lymphatic
• Anti-allergic

Core therapeutic indications for sesquiterpene-rich essential oils:

• allergies
• inflammatory conditions
• rashes and skin irritations
• nervous system imbalances: stress, anxiety, etc.
• smooth muscle spasms

Sesquiterpene-rich essential oils

• Clove bud (Syzygium aromaticum syn. Eugenia carophyllata)
• Copaiba (Copaifera species)
• Ginger Distilled (Zingiber officinale)
• Helichrysum (Helichrysum italicum)
• Myrrh gum (Commiphora myrrha var. molmol)
• Patchouli (Pogostemon cablin)
• Vetiver (Vetiveria zizanioides)
• Yarrow (Achillea millefolium)

Safety for sesquiterpene-rich essential oils

• Essential oils rich in sesquiterpenes tend to be well tolerated by the skin.
• No known safety concerns for sesquiterpenes.
• Individual essential oil monographs will have safety information for that specific essential oil.

Aromatic Chemistry: Overview

“We are stardust, billion year-old carbon, we are golden, and
we’ve got to get ourselves back to the garden”
– Joni Mitchell, Woodstock.

For many students, this is the moment of eye-rubbing and deep sighing. Jumping into the vat of a chemistry lesson can be tedious and painful. Perhaps your feelings about learning some basic chemistry are similar to ones that you feel as you are coaxing yourself into exercising; It is hard to be motivated sometimes. Don’t be disheartened! Chemistry is a part of everything around us. Our food, clothing, shelter, and medicine are all chemical in nature. In fact, all matter is chemistry. It happening to us and within us as at this very moment in time. You are already doing chemistry as you read this sentence, whether you are conscious of it or not!

For our Foundations of Aromatherapy course, we will be providing an overview of the chemistry of essential oils. The goal, at this stage of your learning, is to become familiar with the language of aromatic chemistry. Part of this goal is to learn the basics of each chemical family, the core therapeutic actions for that family, core indications (if any), and any safety concerns. Ok, let’s dive in!

Watch Introduction to Chemistry with Jade

Introduction Part I

Introduction Part 2

Introduction Part 3

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Organic chemistry

Organic chemistry was once known as the study of living organisms and/or the “life force” that emanated from the “living” or “once having lived” organism or substance. This was the basis of vitalism, the belief that natural products needed a ‘vital force’ to create them. Organic chemistry was first known as the study of compounds having a vital force.

In the early half of the nineteenth century, however, a significant event occurred that forever altered the landscape of organic chemistry. In 1828, Friedrick Wohler, a German scientist, effectively broke the barrier between organic and inorganic within the context of its earlier definition by successfully synthesizing the organic compound, urea, from the inorganic substance, ammonium cyanate. From this point on, organic chemistry became the study of chemical compounds of carbon and hydrogen.

Although vitalism was ‘disproved’ in the early nineteenth century, vitalism continues to live in the minds of those who believe that ‘natural’ (plant derived) vitamins, flavor compounds, etc. are somehow different and more healthful than the identical ‘artificial’ (synthesized) compounds. And indeed, this is true among herbalists and aromatherapists. The concept of vital force remains central to homeopathic understanding of disease and the substances used to ‘treat’ it.

The philosophical foundation of Chinese and Ayurvedic medicine established itself in vitalism as both systems rely on a vital force or energy, called Qi or Prana respectively. This vital force permeates not only the individual being but also all living things; it is the principle or dynamo that runs life and so connects all life forms in a living web of interconnections. The human body/mind/spirit, herbal medicine, essential oils, food, and air all carry a vital force that can positively affect the health of the individual, the society, earth, and the culture.

Compounds derived from plants fall into the realm of organic chemistry, which is defined as the scientific study of the structure, properties, composition, reactions, and preparation of chemical compounds of carbon and hydrogen.

The Nature of Organic Molecules

Steve Buhner sums up plant chemistry:

“The carbon atoms that become available from the breakdown of CO2 during photosynthesis form the backbone of all plant chemistry. Plants use this carbon (along with hydrogen, oxygen, and nitrogen) to make their physical structure (whether a huge redwood or a tiny violet growing along a mountain path); primary compounds such as sugar, starch, and chlorophyll; and hundreds of thousands, perhaps millions, of other, complex, secondary compounds: “acids, aldehydes, cyanogenic substances, glycosides, thiocyanates, lactones, coumarins, quinones, flavonoids, tannins, alkaloids, terpenoids, steroids” and more.

Adding to the complexity, all these compounds can be made using different metabolic pathways – different construction techniques, as it were – and each family of secondary metabolites can contain incredible numbers of substances. More than 10,000 alkaloids, 20,000 terpenes, and 8,000 polyphenols are known”.

Carbon is dynamic

As an element, carbon (C) possess unique characteristics relied upon by all living organisms, including the plants we derive essential oils from. In fact, perhaps you have heard the term ‘carbon-based lifeforms’? This element is the basis for life as we know it, so much so that scientists can’t fathom the existence of non-carbon-based life and in our search for life on other planets, carbon-based molecules are considered a key indicator.

One of the most important characteristics of carbon (C) is that it can form multiple bonds with multiple elements. It can bond with not just one, but thousands of other carbon (C) atoms. This ability to bond with almost an endless amount of its own atoms makes carbon (C) capable of creating really large molecules that have many different, complex shapes.

Synopsis of the dynamics of carbon

• Carbon is capable of forming an abundance of complex molecules.
• Carbon can form stable, covalent bonds with other carbon atoms to form chains or rings of various sizes. Strings of carbon atoms are considered to be the backbone or skeleton on which numerous combinations can occur.
• Carbon atoms can form stable bonds with other elements.
• Carbon can form double or triple bonds with other carbon atoms to produce a variety of organic molecules with different properties.
• Carbon can create organic compounds that have the same number and kinds of atoms but completely different structures and thus different properties. This is known is isomerism.

The most common elements to combine with carbon backbones include hydrogen, nitrogen, oxygen. Due to the chemical reactivity of carbon and its ability to bond with other elements, carbon compounds are almost limitless in possibility.

Plants biosynthesize organic compounds

There are thousands of organic compounds biosynthesized within plants, including the volatile components that make up essential oils. Biosynthesis, in this context, means that a plant creates or manufactures diverse organic compounds. These compounds can be grouped into two major classes: primary metabolites such as proteins, carbohydrates, lipids/fats and secondary metabolites such as terpenoids, alkaloids, and phenolic compounds.

Primary metabolites are necessary for the metabolic functioning, growth and development of the organism; whereas secondary metabolites are not considered to be essential for life provide the organism with many benefits and adaptations to ensure fitness. Secondary metabolites largely fall into three classes of compounds: alkaloids, terpenoids, and phenolics. Many thousands of secondary metabolites have been isolated from plants, and many of them have powerful physiological effects in humans and are used as medicines.

The secondary compounds in plants vary by individual species, season, time of day, and environmental stressors. Plants continually receive and process information from their environment and they use it in determining the amounts and types of secondary compounds they need to produce and in what combination.

Plants produce all the metabolites they need both primary and secondary via highly refined biosynthetic pathways that consist of arrays of specific enzymes that concertedly divert the metabolic flow through discrete biosynthetic pathways.

Most of the secondary metabolites, such as terpenes, phenolic compounds and alkaloids are classified based on their biosynthetic origin.

Overview of Biosynthetic Pathways

The principal biosynthetic pathways of importance in studying essential oils include:

1. Products of the Shikimic Acid Pathway
The biosynthesis of shikimic acid
→ Aromatic amino acids
→ Cinnamic and benzoic acids
→ Flavonoids
→ Phenols
→ Quinones
→ Tocopherols
→ Coumarins

2. Products of the MAP (Mevalonate (Mevalonic) Acid) Pathway
Biosynthesis of mevalonic acid and the active isoprene units
→ Sesquiterpenes
→ Triterpenes
→ Squalene
→ Steroids
→ Phytosterols

3. Products of the MEP (Methylerythritol Phosphate) Pathway
Biosynthesis via pyruvate and glyceraldehyde-3-phosphate
→ Monoterpenes
→ Diterpenes
→ Carotenoids (tetraterpenoids)

Physical Characteristics

While learning about the families of chemical components found within essential oils, information on their physical characteristics and general therapeutic activity will be provided.

Physical characteristics are those we can usually perceive through the senses. Physical properties include everything about a substance that does not involve chemical rearrangement, including color, odor, solubility in water (polarity), boiling point and physical state.

Polarity: The “Like Dissolves Like” Principle

Polarity refers to how electrical charge is distributed in a molecule. Think of it like this:

• Polar molecules – have an uneven distribution of electrical charge (one end is more positive, one more negative)
• Non-polar molecules – have an even distribution of electrical charge

This matters because “like dissolves like” – polar substances dissolve in polar solvents, and non-polar substances dissolve in non-polar solvents.

Example: Oil and Water
We all know that oil and water don’t mix. This is because:

• Water molecules are polar
• Oil molecules are non-polar

Why This Matters for Essential Oils:

• Essential oils (as a whole) are mostly non-polar, which is why they don’t dissolve well in water
• Different components within essential oils have different polarities
• Components like monoterpenes are very non-polar
• Components like alcohols and phenols are more polar
• The polarity of components affects how they work in the body and what they dissolve in

The main significance for understanding polarity is ‘that substances with similar polarities can dissolve within one another: like dissolves like.

Polarity and Solubility Table

This graph shows the polarity of potential solvents. Water is the most polar solvent and olive oil is the most non-polar solvent.

For example: Oil and water is the quintessential example of substances which do not dissolve into one another but rather they stay separate. The reason for this is due to water molecules being totally polar and oil molecules being totally non-polar hence they are not soluble in one another.

Another example involves the chemical profile of hydrosols. Hydrosols do not contain components such as monoterpenes or sesquiterpenes due to their non-polar nature which makes the hydrophobic. Aldehydes, alcohols, phenols, ketones, oxides, esters, and phenol methyl ether groups, however, are found in hydrosols at low percentages due to these chemical families being more polar (more soluble in water) in nature.

Water is considered to be the most polar solvent used to extract a variety of chemical components from plants. Vegetable oils, on the other hand, are essentially non-polar solvents.

Solubility can be defined as the ability of a substance to dissolve into another. Solvents used for human consumption and use include water, ethanol, glycerin, various fatty acids (vegetable oils), and acetic acid (vinegar). Essential oils are known to be soluble in vegetable oil, alcohol, ether, and other organic solvents. Essential oils (as whole substances, not isolated components), are not soluble in water.

Essential oils, as whole substances, are considered to be lipophilic (lipo – fat, philic – loving), meaning they are attracted to fatty substances and hydrophobic (water-fearing).

Volatility

Volatility refers to how easily a substance evaporates. Different essential oil components evaporate at different rates, which affects:

• How quickly you smell them
• How long their aroma lasts
• How they’re extracted during distillation

Boiling Point

The boiling point represents the temperature at which a liquid is converted to a gas at a specified pressure. Some components of essential oils come out early in the distillation process while others take a bit longer. This is why, if you distill, you always combine all the water you collected so that it is whole. Each part will hold slightly different molecules.

The fundamental nature of steam distillation is that it enables a compound or mixture of compounds to be distilled (and subsequently recovered) at a temperature substantially below that of the boiling point(s) of the individual constituent(s). Essential oils contain substances with boiling points up to 200° C or higher, including some that are solids at normal temperatures. In the presence of steam or boiling water, however, these substances are volatilized at a temperature close to 100° C at atmospheric pressure.

Other Physical characteristics

The aroma and color of the individual chemical families or components may also be provided when relevant. An example of a component that is a rich blue color is the sesquiterpene, chamazulene and an example of an important component responsible for the aroma of grapefruit is nookatone.

Terpenes and Terpenoids

Terpenes and terpenoids are the most abundant and structurally diverse group of plant secondary metabolites. There are over 22,000 known terpene compounds. They play an important role in plant-insect, plant-pathogen, and plant-plant interactions.

Essential oils contain simple hydrocarbons in the form of terpenes and more complex terpenoids called oxygenated hydrocarbons, or substituted hydrocarbons, in the form of alcohols, phenols, phenylpropanoids, esters, aldehydes, ketones, oxides, sesquiterpene lactones, and furanocoumarins.

The term terpene usually refers to a hydrocarbon molecule (e.g. monoterpenes and sesquiterpenes) while terpenoid refers to a terpene that has been modified, such as by the addition of oxygen (e.g. alcohols, esters, ketones, etc.).

Terpenes are classified according to the number of isoprene units (see Figure 4.1) that their molecules contain. All terpenes and terpenoids are derived by repetitive fusion of branched five-carbon units based on the isopentane skeleton. The isoprene unit is also sometimes referred to as methylbuta-1, 3-diene, and is the molecular structural unit from which unsaturated hydrocarbons are derived. Each isoprene unit contains 5 carbon atoms.

The five-carbon isoprene units are most often joined in a ‘head-to-tail’ fashion, but head-to-head fusions are also common and some products are joined via tail-to-tail fusions.

Terpenes found in essential oils can then be classified as:

• Monoterpenes: 10 carbon atoms (or 2 isoprene units)
• Sesquiterpenes: 15 carbon atoms (or 3 isoprene units)
• Diterpenes: 20 carbon atoms (or 4 isoprene units) **Rarely found in essential oils. The diterpene, sclareol, is found in clary sage in minute quantities.

Hydrocarbons

The simplest organic compounds and the basic backbone of essential oils are hydrocarbons, consisting solely of hydrogen and carbon. Essential oils contain simple hydrocarbons in the form of mono- and sesquiterpenes. Monoterpenes and sesquiterpenes are best known as components of volatile essential oils.

Oxygenated Hydrocarbons

The oxygenated hydrocarbon families are governed by a functional group which provides the family with general physical and chemical attributes. A functional group is an atom or group of atoms that imparts specific chemical and physical properties to a molecule. For example: Alcohols have the functional group, hydroxyl or (-OH).

These functional groups play a large part in determining the pharmacology and toxicology of the essential component; for example, ketones are more active and toxic than alcohols and alcohols and phenols are more potent as antimicrobial agents then ketones.

The table below provides a synopsis of the oxygenated hydrocarbons or terpenoids which will be covered in this course.

Oxidation and essential oil components

One type of chemical change that can be significant is oxidation. In general, oxidation means that a compound has reacted with oxygen from the atmosphere, or has undergone degradation initiated by UV-generated free radicals or reactive oxygen species (ROS). Oxidation is accelerated by heat. Hence, the recommendation that essential oils be stored away from direct sunlight or heat source.

We are all familiar with the concept that vegetable oils go rancid. This is due to oxidation, specifically called lipid peroxidation, which is responsible for the phenomenon of rancidity in vegetable oils and fats.

Mechanism of auto-oxidation and formation of oxidation products
When exposed to air, organic molecules with unsaturated double bonds, such as terpenes, are prone to auto-oxidation. In the initial step of autoxidation of unsaturated molecules, the site adjacent to a double bond is involved. When the allylic hydrogen atom is abstracted, a stabilized radical (R•) is formed which reacts with oxygen, resulting in the formation of a peroxy radical. This peroxy radical can, in turn, abstract a hydrogen atom to form a hydroperoxide while generating a new radical R•, and thus propagating the oxidation chain reaction.

Many terpenes are not protein-reactive or allergenic in their basic form. However, as these molecules autoxidize, they incorporate oxygen in their structures and form primary oxidation products, hydroperoxides, which, in turn form secondary oxidation products, i. e. epoxides, aldehydes, ketones and alcohols. The oxidation products can be allergenic, with the hydroperoxides being strong sensitizers.

Linalool and Limonene

Limonene (from citrus oils) and linalool (from lavender oil) are naturally weak allergens that rarely cause skin reactions. However, when these compounds are exposed to air during normal use, they oxidize and form hydroperoxides—potent skin allergens that significantly increase the risk of allergic reactions.

Specifically:

• Oxidized linalool creates linalool hydroperoxide and linalyl epoxide
• Oxidized limonene produces limonene-1-hydroperoxide and limonene-2-hydroperoxide

This oxidation process explains why essential oils containing these compounds (like lavender or citrus oils) can become more allergenic over time when exposed to air.

For limonene-rich essential oils (e.g. the citrus essential oils), it is best to store them in the refrigerator and replace at least every 1-3 years if stored correctly.

Lavender

Lavandula angustifolia P. Mill.

Watch Presentation on Lavender with Jade Shutes

Listen to Jade discuss the beauty and amazing therapeutics of Lavender – Part I

Lavender – Part II

BOTANICAL INFORMATION

Common names: Lavender, English lavender
Scientific name: Lavandula angustifolia Mill.
Synonyms: Lavandula officinalis Chaix syn. L. vera DC.
Botanical family: Lamiaceae
Conservation status: Least concern¹

Description: Lavandula is a genus in the Lamiaceae family that includes about 30 species of small flowering evergreen shrubs. Lavenders are native to the Mediterranean, and have been naturalized and cultivated throughout much of the world. The leaves are linear, hoary, and grey-green, while the flowers are purple and sparsely arranged at the tips of long bare stalks. Lavender’s aroma arises from shining oil glands interspersed amongst the tiny star-shaped trichomes that cover the plant’s flowers, leaves, and stems. The most widely cultivated species of the Lavandula genus include English lavender (Lavandula angustifolia), French lavender (L. stoechas), and woolly lavender (L. lanata).

Lavender essential oil is distilled from the flowers, and is used in perfumery and cosmetics, and to flavor beverages, sweets, and ice creams. Dried lavender flowers have long been used in sachets to scent chests and closets.²

Ethnobotany: Lavandula has a long tradition of medicinal usage. The notion that ancient Romans used lavenders in their baths is widely disseminated, and thus the common name lavender is thought to arise from the Latin lavare, “to wash.” Reference to lavender flowers and oil have not been found in comprehensive reviews of Roman bathing practices, however, and the attribution is likely apocryphal.

One 17th century Persian medical text describes lavender as “the broom of the brain,” as it is thought to “sweep away impurities.” An Indian medical text dating to the 8th century BCE includes lavender in various psychiatric formulas as an edible ointment or medicinal butter. These traditional preparations are still used in modern Tibetan Buddhist medicine to relieve insanity and psychosis. In European systems of traditional herbal medicine, lavender was primarily used in teas, baths, and pillows as a mild sedative and gentle nervine. Lavender has also been valued in European folk medicine for its spasmolytic, carminative, stomachic, and diuretic properties. Lavender flowers have been used as a remedy in laryngitis, asthma, sinusitis, and candida infections. Lavender oil massaged into the temples is a traditional remedy for headache, and the oil is thought to ease muscular pain. It is used topically to heal insect bites, burns, and small cuts.³

EXTRACTION INFORMATION

Country of origin: France, Bulgaria, England, USA
Part of plant used: Flowering tops
Extraction method: Distillation
Essential oil yield: 0.5 – 3%
Color of oil: Clear

AROMATIC CHEMISTRY

Seventy-seven+ components make up 97.3% of the essential oil of Lavandula angustifolia. The core components include: linalool (25-38%), camphor (11%), linalyl acetate (25-45%).

Monoterpenes: limonene (<1-8.5%), a-pinene (0.2%), a-thujene (0.6%), a-terpinene (0.3%), b-ocimene (2.5-6%)
Sesquiterpenes: b-caryophyllene (3-12%)
Esters: linalyl acetate (27.5%), bornyl acetate (0.1%), lavandulyl acetate (3.4-6.2%), neryl acetate (2.0%), geranyl acetate (3%)
Monoterpenols: linalool (27.2%), borneol (2.5%), terpinen-4-ol (2.1-6%), a-terpineol (<2-4.2%)
Ketones: camphor (0.5-1%)
Ethers (oxides): 1,8 cineole (1-2%), cis-linalool oxide (2.4%)⁴

SAFETY INFORMATION

• No known contraindications
• GRAS status

THERAPEUTIC ACTIONS

SYSTEM AFFINITIES

Nervous, Skin

BLENDING INFORMATION

Aroma description: Fresh, floral, sweet, herbaceous
Blending factor: 7
Note: Mid note
Blends well with: Most essential oils.

CORE INDICATIONS

• Cardiovascular system: hypertension, heart palpitations (from anxiety), tachycardia (I+++, C+, D+++)
• Digestive system: stress-related digestive upsets, including irritable bowel syndrome, abdominal cramps, nervous stomach (O+++, I+++, C+++)
  
• Musculoskeletal system: muscular aches and pains, arthritis, sprains, strains, muscle spasms, growing pains, plantar faciitis, tendonitis, shin splints, rheumatic conditions, joint pain and stiffness, bursitis, cramps (C+++)
• Nervous system: restlessness, insomnia, stress, shock, headaches, migraines, neuralgia, nausea, stress related disorders (O+++, I+++, C+++, D++)
• Reproductive/endocrine system: calms during delivery, can help reduce severity of contractions (use with clary sage), helps in relieving pain, menstrual cramps, PMS, perineal discomfort and repair following childbirth, wound healing from episiotomy (O+++, C+++, I+++, D++)
• Skin: burns (recommend using Lavandula latifolia instead or in conjunction with), scrapes, abscesses, acne, athlete’s foot, eczema, inflamed skin conditions, psoriasis (as an anti-inflammatory), sunburn, relieves itching, insect bites, hives, open wounds or sores, poorly healing wounds, allergy (expressed on the skin), razor burn, stretch marks (C+++)
• Psyche/emotion: calming, soothing, nurturing, irritability, balancing, personal renewal, useful in treating depression (including manic), anxiety, hyperactivity, alleviates fears and delusions, extreme emotions, panic attacks, hysteria, fainting, challenging behavior, limited communication skills, fear of touch, disturbed sleep patterns (I+++, D+++, O+++, Fb+++)
  __________________
• Ayurveda: In Ayurvedic terms, the effect of lavender oil could be described as pacifying to vata (calms, relaxes, and restores the nervous system) and cooling to pitta (anti-inflammatory). It is a highly sattvic oil, meaning that it purifies aggravated emotional states and helps bring mental peace. Lavender Shirodhara showed potent anxiolytic and Altered State of Consciousness-inducing or promoting effects, and induced the largest increase in foot skin temperature.⁵
• Traditional Chinese Medicine: Calming to shen, cooling to liver heat, relaxing to liver chi stagnation. For stagnation of liver chi, liver wind, damp heat in the liver and gallbladder, liver Yang rising, heart fire, kidney Yin deficiency with heat.

RESEARCH

Human Studies

• A combination of lavender, clary sage, and marjoram provides relief for individuals with dysmenorrhea and reduces menstrual pain.

A study published in the Journal of Obstetrics and Gynaecology Research in 2012 found that abdominal self-massage with essential oils provided relief for outpatients with PD and reduced the duration of menstrual pain. 48 outpatients diagnosed with PD by a gynecologist were divided into two groups. The experimental group received essential oils of lavender, clary sage, and marjoram in a 2:1:1 ratio diluted to 3% in an unscented jojoba cream at a dosage of 2 g/day, while the control group was given a synthetic fragrance diluted in jojoba cream. Demographically, the participants ranged in age from 19-45 years, 77% had experienced dysmenorrhea for over three years, and 50% of the participants had never used analgesics. One criterion of inclusion was that participants had at least one menstrual cycle in the previous year, which the authors charmingly referred to as a “menstrual experience.”

Pain levels were evaluated with a 10-point numeric rating scale (NRS) and verbal rating scale (VRS) pre-intervention, on the first three days of the first menstrual cycle concurrent with the intervention, and post-intervention on the first three days of the subsequent cycle. The researchers observed a statistically significant reduction in the duration of pain in the aromatherapy group but not in the synthetic fragrance group, as well as a greater drop in the severity of pain from the first to the third days of menstruation. None of the participants in the aromatherapy group required analgesics after the intervention.

The researchers also performed gas chromatography on the essential oil blend to identify constituents and found the top five contents to be: linalyl acetate (36.84%), linalool (22.53%), eucalyptol (17.21%), ɑ- terpineol (3.29%), and β-caryophyllene (2.69%). The analgesic effects of the essential oil blend are attributed to these compounds. The authors attempt to tease out potential confounding factors of the effects of massage, writing:

Massage can reduce stress hormone levels by excreting endorphins in the plasma, promoting parasympathetic activation, and increase secretion of the neurotransmitter serotonin to block the conduction of pain. Indeed, massage may possess positive influences on relieving menstrual pain. However, it has no persistent analgesic efficacy, only temporary efficacy… The efficacy of pain relief was due to certain components in the massage cream, and not to the practice of massage itself in our study.

The authors note that aromatherapy has a “positive influence on the autonomic nervous system, releasing anxiety, and controlling pain,” an outcome they attribute not just to the scent of the essential oils, but to transdermal absorption of their chemical constituents. The mechanism of action likely involves inhibition of prostaglandin secretion by linalool, which results in decreased myometrial contractility. Eucalyptol (1,8-cineole), a terpene oxide found in marjoram oil, inhibits the metabolism of arachidonic acid, a precursor to PGs found to have inflammatory effects on human blood monocytes. β-caryophyllene, a terpene, also exerts local anesthetic activity.⁶

• A combination of Lavender, Clary sage and Rose decreases menstrual cramps.

A randomized placebo-controlled trial published in 2006 in the Journal of Alternative Complementary Medicine found that abdominal self-massage with almond oil and aromatherapy was more effective at relieving dysmenorrhea than almond oil self-massage alone. In this study 67 college students with a menstrual pain ranking of 6/10 or higher on the visual analog scale were divided into experimental, placebo, and control groups. The experimental group performed self massage with 5 cc of almond oil to which essential oils had been added: 2 drops lavender (Lavandula officinalis), 1 drop rose (Rosa centifolia), and 1 drop clary sage (Salvia sclarea). The placebo group performed self massage with 5 cc of almond oil, while the control group received no treatment. Intensity of pain was measured via the visual analog scale, while severity of dysmenorrhea symptoms were assessed with a multidimensional scoring system designed to assess the impact of dysmenorrhea on daily life. Aromatherapy self massage was found to reduce the intensity of menstrual pain compared to placebo and control, as well as to significantly reduce the severity of dysmenorrhea impact on the first and second days of menstruation. Aromatherapy treatment resulted in a pain score drop from 7.40 to 4.26 on the first day of menstruation.⁷

One limitation of these studies is the inconsistency inherent in self massage as part of a treatment protocol. A 2012 study published in the journal of Pain Management Nursing controlled for this variable by having one practitioner perform abdominal massage on all the participants at a regularly scheduled time of day. In this trial, standardized abdominal massage with lavender oil was found to be more effective at reducing menstrual pain than massage with odorless liquid petrolatum. The experimental design consisted of a randomized crossover design, wherein 44 volunteers with PD received 15 minutes of abdominal massage with lavender oil or placebo oil. The results were measured via visual analog scale at baseline and post-treatment. Participants were monitored for three menstrual cycles: One observational period without treatment, followed by treatment/placebo for the next cycle, with the treatments swapped across groups in the third cycle. A reduction in pain was observed in both placebo and experimental groups, but the degree of pain reduction was significantly greater in the lavender oil group than the petrolatum group: pain levels as measured by a 100-point VAS scale dropped from 82.38 to 51.13 after aromatherapy massage, compared with 82.38 to 74.31 after placebo massage.⁸

Aromatherapy has also been shown to be effective in treating dysmenorrhea in the absence of abdominal massage, through inhalation alone. The Annals of Medical and Health Sciences Research published a study in 2016 on the effect of lavender aromatherapy on pain severity in primary dysmenorrhea. In this triple-blind randomized clinical trial, 200 individuals between the ages of 19 and 29 with PD were divided into two groups. One was exposed to lavender essential oil and the other to diluted milk as a control. Each group received 10 cc of their respective substance and were instructed to drip three drops onto a piece of cotton, and to smell it once daily for 30 minutes on the first three days of their cycle for two consecutive cycles. Pain was quantified via the visual analog scale which was submitted via questionnaire on the cycle previous to treatment (Cycle-0), and the two subsequent cycles. The researchers found that the group exposed to lavender essential oil experienced a statistically significant reduction in pain over the course of two cycles as compared to the control group, which had no such reduction. Pain levels were comparable between the two groups prior to treatment.⁹

Another randomized clinical study published in Complementary Therapies in Medicine in 2014 found that inhalation of lavender essential oil significantly reduced symptoms of primary dysmenorrhea. In this study 96 Iranian students suffering from PD were divided into two groups. The experimental group was given lavender essential oil diluted in sesame oil at a ratio of 2:1, while the placebo group used sesame oil alone. The subjects were instructed to place three drops of the oil on their palms, rub them together, place their hands at a distance of 7-10 cm from their noses, and inhale for five minutes. This treatment was administered one hour following the onset of dysmenorrhea symptoms, and repeated every six hours for the first three days of menstruation for two consecutive menstrual cycles. Results were measured via a researcher-developed questionnaire based on existing dysmenorrhea literature and designed to assess symptoms intensity from light to severe/debilitating. The volume of menstrual bleeding was measured by a pictorial blood assessment chart before and after treatment. Researchers found that inhalation of lavender significantly reduced symptoms of dysmenorrhea compared to placebo. Menstrual volume was reduced, though the data was not statistically significant, and there was no effect of lavender inhalation on the presence of blood clots.¹⁰

• Inhalation of lavender (scientific name not given) essential oil relieves anxiety and reduces cortisol levels in candidates for open-heart surgery.¹¹
• Inhalation of lavender (Lavandula angustifolia) essential oil reduces stress and improves sleep quality in patients in intensive care unit.¹²
• Inhalation of lavender (Lavandula angustifolia) essential oil exhibits relaxing activity.
  The results revealed that lavender oil caused significant decreases of blood pressure, heart rate, and skin temperature, which indicated a decrease of autonomic arousal. In terms of mood responses, the subjects in the lavender oil group categorized themselves as more active, fresher relaxed than subjects just inhaling base oil.¹³

Animal Studies

• Lavender (Lavandula angustifolia) essential oil exhibits anxiolytic and sedative activity.^14,15
• Lavender (Lavandula angustifolia) essential oil exhibits anxiolytic activity.^16,17,18
• Lavender (Lavandula angustifolia) essential oil exhibits local analgesic activity.¹⁹
• Lavender (Lavandula angustifolia) essential oil exhibited an anti-stress effect and decreased anxiety and social avoidance without intense causing intense sedation.²⁰
• Lavender (Lavandula angustifolia) essential oil exhibits anti-inflammatory activity.²¹
• Dermal application of lavender essential oil (2% dilution) reduced inflammation and exhibited anti-nociceptive activity.²²

Watch: Introduction to Essential Oil Monographs with Jade Shutes

Cultivating our relationship with essential oils

Essential oils are at the heart of our practice as aromatherapists, our core tools for supporting health and wellness as well as for treating imbalances and pathophysiological states. With so much information (both good and bad) being conveyed through social media about different essential oils, along with a growing emphasis on chemistry and biomedical/pharmaceutical derived information for their toxicity and therapeutic actions, it is our responsibility to ensure we have a strong foundation in our knowledge and experience of each essential oil we use so as to better integrate and evaluate the information or infographics we may come across.

Cultivating a personal relationship with each essential oil in one’s repertoire of aromatics is therefore paramount. Beyond the above reasons, cultivating a personal relationship with each essential oil provides you with the confidence and empowerment in using them for diverse clients and a wide range of health conditions or imbalances.

The aromatherapy monographs have been created to provide you with a range of information that supports and encourages this relationship.

Each essential oil monograph covers the following information:

BOTANICAL INFORMATION

Common names: Sweet Marjoram
Scientific (Latin) name: Origanum majorana L.
Botanical family: Lamiaceae
Conservation status: Not defined

Nomenclature and conservation status: The first part of the plant monograph informs us about the plant’s classification and nomenclature: its vernacular names, Latin name, the botanical family, and, and the conservation status of the plant. In the above example, the vernacular name is: sweet marjoram.

Common names, otherwise known as vernacular names, are included so you can link common names with the Latin.

The Scientific (Latin) name is composed of the genus, in this case Origanum; the species name, majorana; and the botanist who first described the plant noted with an abbreviation such as ‘L.” (L. refers to the botanist, Linnaeus). The Latin name can provide a lot of useful information. It is more precise than common names, which can be ambiguous: the same common name can apply to different plants, and the same plant can be known by different common names. Each plant only carries one valid Latin name, but the Latin names are updated from time to time. Sometimes we commonly refer to a plant by its previously accepted Latin name. To accommodate this, we may list the previously accepted (and older) Latin names as synonyms.

Sweet marjoram (Origanum majorana) belongs in the family known as the Lamiaceae. An awareness of plant families will help you create a framework through which you can derive similarities in traits, either physical or biochemical.

*Find names of botanist by their initials here: https://en.wikipedia.org/wiki/List_of_botanists_by_author_abbreviation_(P)

Occasionally a plant has more than one botanical name which is represented with the word syn or synonym which means ‘the same as’. *All Latin names have been verified by using: Germplasm Resources Information Network and the United States Department of Agriculture, Natural Resources Conservation Service.

Botanical family: Each essential oil bearing plant belongs to a specific botanical family. Often a group of plants within one given botanical family will have common characteristics, whether chemically or in therapeutic action. Occasionally there are two names, one followed by the word ‘syn’, meaning ‘the same as’. The first name is the most current and accepted name while the second one is its formerly accepted name. This can be helpful in researching an essential oil as information will be listed under both the older and modern names.

Conservation status:

The conservation status informs us to what degree a plant is likely to become extinct in the wild. The medicinal use of plants is responsible for the depletion and even extinction of wild plants. Information on conservation status is taken from the IUCN Red List, which defines extinction risk using criteria such as areas of occupancy, population numbers, reproductive rate and success, current and projected threats to the species and its habitat, and so on.

Conservation status ranges from Least Concern, which means the plant is not threatened, all the way to Extinct, meaning it has disappeared completely. In between these extremes are Near Threatened, Vulnerable, Endangered, Critically Endangered, and Extinct in the Wild. This information should guide which plants (essential oils) you use and how you source them.

Extraction Information

Country of origin: The country of origin reflects the country where the essential oil is either indigenous or where it is cultivated or harvested in the wild for the express purpose of distilling and yielding an essential oil. The country of origin can considerably affect the chemical composition of the essential oils.

The country of origin can also have an affect, or perceived effect, on the quality of the oil produced. For instance, most aromatherapists believe Bulgarian rose (Rosa damascena) to be far superior to Turkish rose of the same species & Lavender (Lavandula angustifolia) from the high altitudes of France to be superior to the Tasmanian, Croatian, or American essential oil from the same species. Although it is true, the evaluation of the aroma of the rose, for example, is in the nose of the one who is smelling!

Part of plant used: This is the part of the plant distilled to obtain the essential oil. Note: The term ‘flowering tops’ means that the flowers and top leaves are distilled.

Extraction method: The most common method of extraction for that particular plant

Essential oil yield: (v/w) ¥ (v/w) This means the yield of essential oil in volume, typically milliliters per 100 grams of plant material. Thus, the yield is dependent upon the amount of plant matter processed. For instance, geranium 0.3- to 2% per 100 grams. This means one would yield approximately 0.3 to 2 mls of essential oil per 100 grams of plant material by weight.

Occasionally, the yield will be given in w/w terms which means the yield of essential oil in weight (grams) per 100 grams of plant material.

The essential oil yield as well as the chemical composition of an essential oil is influenced by environmental factors such as moisture, temperature, light intensity, soil type, salinity of soil, nutrition, and the amount of sunlight the plant receives. Other factors include genetics, abiotic and biotic stressors.

Color of oil: A description of the color range of the individual essential oil

AROMATIC CHEMISTRY:

Essential oils may contain over 200+ unique chemical components, many of which may appear at less then 1%. Each essential oil has, what are considered to be, active or major chemical components that influence its therapeutic activity and behavior. In this section, the major components are provided.

NOTE: The chemical composition of any individual essential oil can vary greatly depending on country of origin, environment, harvest time, etc.

As aromatherapist, we are able to generalize some of the therapeutic activity of an essential oil via the chemical family or families of components most present in a given essential oil. We are also able to obtain insight into the therapeutic activity of an essential oil due to the presence of specific components.

For instance, an essential oil rich in esters is considered to be generally calming to the nervous system whereas an essential oil rich in phenols will be highly effective as an antimicrobial agent. We could be even more specific by stating something like: The active components of Lavandula angustifolia essential oil are linalool (a monoterpene alcohol) and linalyl acetate (an ester). These components contribute to the sedative and anti-inflammatory activity of Lavandula angustifolia essential oil.

SAFETY INFORMATION

This section lists the current safety data for the essential oil.

THERAPEUTIC ACTIONS

This section details the therapeutic activity of the essential oil. The actions listed are those that have either empirical acceptance or that can be supported by research. Please note that some of the research references are placed in this section. This research is typically based upon in vitro or animal studies unless otherwise noted. The core actions for which the essential oil is most used and known for within aromatherapy practice are highlighted in bold text.

SYSTEM AFFINITIES

An essential oil often displays a certain affinity with a specific system, organ, or function. In this section, we list the core systems of the body for which the essential oil has an affinity. Herbs and essential oils often have a predilection for a certain organ or function. This is called a tropism.

BLENDING INFORMATION

• Aroma description: The general description of the aroma of the individual essential oil
• Blending factor: The blending factor is a tool designed to support the formulation of balanced blends and synergies.
• Notes: The note theory was adopted from the perfume industry. Base notes evaporate more slowly than top notes. Base notes are used as fixatives while top notes represent the first aroma smelled. Mid notes are used to balance the blend in perfumery.

CORE INDICATIONS

This section is designed to list the most common and traditional uses of the essential oil. Like the Therapeutic actions section, these indications are those which can be supported by either strong empirical (experience or clinical practice), clinical research, or other relevant research.

The core indications are listed first for systems of the body and then for emotion/psyche applications. They are not in any particular order of importance or effectiveness.

CODES

In the Core Indications section after each system there are one or more codes such as C+++, O++, or D+. These codes indicate route of administration (e.g. C – cutaneous) and whether that method is highly recommended, recommended or supportive. The chart below outlines the codes used throughout the monographs on essential oils.

RESEARCH

The use of scientific research to support various properties of essential oils is in vogue in todays aromatherapy community. Often however, there is little clarity as to whether the study as on humans, animals, or in vitro. The School for Aromatic Studies monographs clearly present Human studies, Animal studies, and In vitro studies. When possible, a link has been provided in the Reference section noted with: ‘Retrieved from’. Other papers have been purchased and are unable to be shared.

Watch: Safety and Essential Oils: Part One with Jade Shutes

Watch: Safety and Essential Oils: Part Two with Jade Shutes

Watch: Safety and Essential Oils: Part Three with Jade Shutes

A Positive Approach to Essential Oil Safety

A therapeutic, knowledge, and experiential-based model for safety

With so much emphasis these days on safety and essential oils, it seems that the challenge isn’t really about ‘more safety’ but rather how we relate to it, how shall we interpret it so that it makes sense in our practice or general use of essential oils? And how shall we find balance within the extremes that appear on social media?

I like to begin with this idea: Essential oils are safe. It seems simple enough, right? And yet, there are three caveats:

1. Essential oils are safe when selected appropriately for the client or purpose of the product (includes target audience).
2. Essential oils are safe when the appropriate route of administration (oral, cutaneous, inhalation/diffusion), as well as the method of application (baths, herbal eo capsules, inhaler, etc.), is chosen correctly for the client or purpose of product.
3. Essential oils are safe when the dilution/dosage, length of time, and intensity of treatment is based upon the individual’s constitution, the essential oils being used, the nature of the condition, and the goal of the treatment.

Essential oils are powerful. They speak on multiple levels (physiologically and emotionally) to the human organism and are capable of widely diverse yet complementary therapeutic actions (antispasmodic, anti-inflammatory, etc.). We need to respect them, and yet we also need to appreciate that we have a long history, that we actually co-evolved with aromatic plants, and that they have been our allies as food, as shelter, in magic or ritual, as aromas and olfactory delight, and as medicine. We have a symbiotic relationship. But like all relationships, we must cultivate our inherent respect for their power, their potency and to use them accordingly.

With this in mind, we have adopted Peter Holmes’s approach to safety and essential oils. Like us, Peter is reframing aromatherapy with a model utilizing Traditional Chinese medicine (TCM) as his language. We are using Western herbal energetics. The goal is the same. To offer another way of viewing and being in relationship with essential oils, how we use them, how we relate to them, and how we practice or frame imbalances in the body.

Moving along with safety, I very much like the way Peter Holmes has created three general therapeutic status categories. The general therapeutic status is a system that allows us to present essential oils in three unique categories based upon their individual ‘nature as a natural remedy in terms of its therapeutic applications at the most basic level.’

We will be using these categories to inspire a new way of viewing and relating to the safety of essential oils: one through the lens of the knowledgeable, responsible, reflective, and empowered aromatherapist and essential oil therapist.

We must understand both the essential oils benign qualities
as well as it potential for toxicity.

– Peter Holmes

Category 1: Mild essential oils

The essential oils included in this category do not present any significant risk of toxic accumulation in any part or system of the body, even when administered over a long period of time. Aside from the essential oils, which may be dermal irritants, sensitizers, or photosensitizers, this group of essential oils poses little concern even for the small amounts of various components that may be absorbed via the cutaneous route into general blood circulation. The vast majority of essential oils are included in this category.

Mild Essential oils: Lavender (Lavandula angustifolia), Petitgrain (Citrus x aurantium var. amara), Citrus essential oils (Citrus limon, C. paradisi, C. reticulata, Citrus bergamia, etc.), Coriander seed (Coriandrum sativum), Peppermint (Mentha x piperita), Tea tree (Melaleuca alternifolia), Ginger (Zingiber officinale), Roman chamomile (Chamaemelum nobile), Frankincense spp., Sweet marjoram (Origanum majorana), Melissa officinalis, Litsea cubeba, Black spruce (Picea mariana), Cedarwood (Cedrus atlantica), Vetiver (Vetiveria zizanioides), Sandalwood (Santalum sp.), German chamomile (Matricaria recutita), Lavandin (Lavandula x intermedia), Clary sage (Salvia sclarea), Neroli (Citrus aurantium var. amara)

Category 2: Medium-strength essential oils

This group of essential oils presents some potential or risk of toxic accumulation of certain components, even when taken at the accepted therapeutic dose. The essential oils below should be used with caution. For internal routes, only short-term (less than 3 months) use is recommended. Caution is assumed for the cutaneous route; avoid daily long-term application.

*Specific components have been reviewed in the chemistry module.

The most common toxicity concern is neurotoxicity, regardless of the route of administration. Essential oils in this category are contraindicated during pregnancy or while breast-feeding.

Essential oils with potential to become neurotoxic

• Sage (Salvia officinalis) – thujone (⍺- and β-) and camphor
• Rosemary ct. verbenon (Rosmarinus officinalis) – verbenone
• Hyssop ct. pinocamphone (Hyssopus officinalis) – pinocamphone
• Spearmint (Mentha spicata) – carvone
• Rosemary ct camphor (Rosmarinus officinalis) – camphor

Category 3: Strong essential oils

Essential oils in this group can cause acute poisoning regardless of the route of administration. The oral use of these essential oils should be avoided due to the potential for liver and nervous system toxicity.

Essential oils with potential for acute toxicity:

• Wormwood (Artemisia absinthium) – thujone
• Cedar leaf (Thuja occidentalis) – thujone
• Penny royal (Mentha pulegium) – pulegone

Along with these categories, it is important to also known
any safety concerns for each individual essential oil you are formulating
with as well as dermal safety covered below.

Let’s begin by putting safety into context.

Safety and Essential Oils

Safety involves a state of being free from risk or occurrence of injury, harm, or danger. Individuals who practice aromatherapy need to be aware of the safety issues involved with using essential oils in order to avoid potential adverse effects. Although many essential oils are potentially hazardous materials, if handled in the appropriate manner, the risks involved in their use can be very small. So, therefore, most commercially offered essential oils are safe to use for the purpose intended in a domestic/ professional or clinical environment. Schnaubelt states that the “informed use of essential oils may create occasional irritation or minor discomfort, but it is extremely unlikely to create serious injury or lasting physical problems,” particularly when basic guidelines are followed.

Factors which influence the safety of essential oils include:

1. Quality of essential oil being utilized:

As stated at the beginning of this unit, adulterated essential oils increase the likelihood of an adverse response, and hence, the need for pure, authentic, and genuine essential oils is of the utmost importance. This is not to say that authentic organic essential oils are incapable of triggering an adverse reaction but simply to highlight that adulterated essential oils are more likely to increase the likelihood of an adverse reaction/response.

2. Chemical composition of the oil:

Essential oils rich in aldehydes (e.g., citronellal, citral) and phenols (e.g., cinnamic aldehyde, eugenol) may cause skin reactions. Oils rich in these constituents should always be diluted prior to application to the skin. According to Schnaubelt, “diluting such oils so that the resulting solution becomes non-irritant may require diluting them to concentrations much lower than in normal circumstances. Another option is to blend such irritant oils asymmetrically with other essential oils, which mitigate their irritant effects.” For further details, see Module 4: An Introduction to the Chemistry of Essential Oils.

3. Method of application:

Essential oils may be applied on the skin (dermal application), inhaled, diffused, or taken internally. The potential safety concerns with dermal application will be discussed below. With regards to inhalation, inhalation, from a safety standpoint, presents a very low level of risk to most people. Even in a relatively small, closed room, and assuming 100% evaporation, the concentration of any essential oil (or component thereof) is unlikely to reach a dangerous level, either from aromatherapy massage or from essential oil vaporization.

The only likely risk would be from prolonged exposure (perhaps 1 hour or more) to relatively high levels of essential oil vapor, which could lead to headaches, vertigo, nausea, and lethargy. With regard to internal use, this method of application is not discussed in this foundation’s aromatherapy program, and further training is recommended prior to using essential oils internally. (See our Internal Use of Essential Oils program)

4. Dosage/dilution to be applied:

Most aromatherapy blends for massage and bodywork will be between 1 and 5 percent dilutions, which typically does not represent a safety concern. As one increases dilution, potential dermal (skin) reactions may take place depending on the individual essential oil, the area in which the oil is applied, and other factors related to the client’s own sensitivity levels. Any excessive usage of essential oils may cause irritation or other undesired effects due to their lipophilic nature.

5. Integrity of skin:

Damaged, diseased, or inflamed skin is often more permeable to essential oils and may be more sensitive to dermal reactions. It is potentially dangerous to put undiluted essential oils on damaged, diseased, or inflamed skin. Under these circumstances, the skin condition may be worsened, and larger amounts of oil than normal will be absorbed. Sensitization reactions are also more likely to occur.

6. Age of client:

Infants, toddlers, and young children are more sensitive to the potency of essential oils, and safe dilutions include .5 – 2.5%, depending on the condition. Also, some essential oils should simply be avoided for this population, e.g., Birch or Wintergreen, which are both rich in methyl salicylate. Elderly clients may also have more sensitive skin, so a reduced concentration /dosage may be indicated.

Possible Dermal Reactions

Of primary importance to aromatherapists is the safety of essential oil application to the skin. Skin reactions take three main forms: irritation, sensitization, and phototoxicity.

Dermal Irritant

A dermal irritant will produce an immediate effect of irritation on the skin. The reaction will be represented on the skin as blotchy or redness, which may be painful to some individuals. The severity of the reaction will depend on the concentration (dilution) applied.

General safety guidelines include avoiding the application of known dermal irritant essential oils on any inflammatory or allergic skin condition, avoiding undiluted application, avoiding application on open or damaged skin, and diluting known dermal irritants with appropriate vegetable oil or other carrier. If you suspect a client has sensitive skin, perform a skin patch test (see below). Table 2.1 lists some common essential oils considered to be dermal irritants.

Dermal Sensitization

The most common skin reaction to fragrance materials is sensitization, or ACD, which shows on light-colored skin as a bright red rash, and on darker-colored skin as a darker area. This is the visible sign of tissue damage caused by substances such as histamine released in the dermis due to an immune response. Two types of sensitization happen with essential oils: Immediate hypersensitivity and delayed hypersensitivity.

With immediate hypersensitivity, the reaction occurs rapidly after ‘fragrance’ has been applied to the skin. The reaction is mediated by IgE antibodies, which bind to the surface of mast cells. Within minutes of skin contact with an antigen, the mast cells release histamine and other factors, causing an inflammatory reaction.

With delayed hypersensitivity, little or no effect is evident on first exposure to a substance. On subsequent exposure to the same material, an inflammatory reaction occurs just as rapidly as for the immediate hypersensitivity.

The problem with dermal sensitization is that once it occurs with a specific essential oil, the individual is most likely going to be sensitive to it for many years and perhaps for the remainder of his/her life. The best way to prevent sensitization is to avoid known dermal sensitizers and avoid applying the same essential oils every day for lengthy periods of time (e.g., every day for over 3 months). Tisserand and Balacs note that “sensitization is, to an extent, unpredictable, as some individuals will be sensitive to a potential allergen and some will not.”

The following oils listed in Table 2.2 are considered to be dermal sensitizers.

Photosensitization

Photosensitization, is a reaction to a substance applied to the skin that occurs only in the presence of UV light in the UVA range. An essential oil that exhibits this quality will cause burning or skin pigmentation changes, such as tanning, on exposure to sun or similar light (ultraviolet rays). Reactions can range from a mild color change through to deep weeping burns. Do not use or recommend the use of photosensitizing essential oils prior to going into a sun tanning booth or the sun. Recommend that the client say out of the sun or sun tanning booth for at least twelve hours after treatment if photosensitizing essential oils were applied to the skin.

Certain drugs, such as tetracycline, increase the photosensitivity of the skin, thus increasing the harmful effects of photosensitizing essential oils under the necessary conditions. Table 2.3 lists some common essential oils considered to be photosensitizers and Table 2.4 lists non-phototoxic citrus essential oils.

The image below was taken by a student who used bergamot massage oil on her stomach before going into the sun.

Idiosyncratic irritation or sensitization

Idiosyncratic irritation or sensitization is an uncharacteristic or unusual reaction to a commonly used essential oil. This type of reaction is difficult to predict and rarely occurs but is a possibility.

Mucous membrane irritant

A mucous membrane irritant will produce a heating or drying effect on the mucous membranes of the mouth, eyes, nose, and reproductive organs. It is recommended that mucus membrane irritating essential oils not be used in a full body bath unless placed in a dispersant first (e.g., milk, vegetable oil). Bay, clove, cinnamon bark, lemongrass, and thyme ct. thymol essential oils should be avoided in baths completely. Table 1.5 lists some common essential oils considered to be mucous membrane irritants.

Other Safety Considerations

Safety during pregnancy

The use of essential oils during pregnancy is a controversial topic and one that is yet to be fully understood. The main concern during pregnancy appears to be the risk of essential oil constituents crossing over into the placenta. According to Tisserand, “crossing the placenta does not necessarily mean that there is a risk of toxicity to the fetus; this will depend on the toxicity and the plasma concentration of the compound.” Burfield states “it is probable that essential oil metabolites cross the placenta due to the intimate (but not direct) contact between maternal and embryonic or fetal blood.” He goes on to say, “to my thinking the responsible attitude is to discourage the use of essential oils completely during the first few months of pregnancy.”

Buckle comments that “the use of essential oils in pregnancy is a contentious subject, especially during the vital first 3-month period. It is extremely unlikely that a nightly bath containing a few drops of essential oils will cause any problems for the unborn child.” and later states, “There are no records of abnormal fetuses or aborted fetuses due to the ‘normal’ use of essential oils, either by inhalation or topical application.”

According to Wildwood, “A common myth in aromatherapy is that massage oils containing essential oils such as Clary sage, rose or even rosemary can cause a miscarriage and hence should be avoided throughout pregnancy.” Authors such as Ron Guba, Kurt Schnaubelt, and Chrissie Wildwood have all pointed out that there have been ‘no recorded cases of miscarriage or birth defect resulting from aromatherapy massage using therapeutic applications of any essential oil.’

Guba points out that toxicity during pregnancy is “almost exclusively due to pregnant women taking large, toxic doses of essential oils, notably pennyroyal (rich in the ketone, pulegone, which is metabolized to the highly toxic furan epoxide, menthofuron) and parsley seed (rich in the dimethyl ether, apiol) in an attempt to abort the fetus.” And Battaglia shares this insight: “the judicious use of essential oils together with appropriate forms of massage by a skilled therapist can help ease the discomforts of pregnancy and provide a sense of nurturing that will comfort the mother at times she is likely to be feeling rather fragile.”

Due to the lack of clear information regarding the toxicity of essential oils during pregnancy, it would be best to adhere to general safety guidelines. According to Tisserand, the following essential oils should not be used during pregnancy: wormwood, rue, oak moss, Lavandula stoechas, camphor, parsley seed, sage, and hyssop.

Essential oils that appear to be safe include cardamon, German and Roman chamomile, frankincense, geranium, ginger, neroli, patchouli, petitgrain, rosewood, rose, sandalwood, and other nontoxic essential oils. It would also be prudent to avoid the internal or undiluted application of essential oils throughout pregnancy or only under the guidance of a healthcare practitioner who is trained to practice in this way.

General Safety Precautions

1. Keep all essential oils out of reach of children.

2. Do not use or recommend the use of photosensitizing essential oils prior to going into a sun tanning booth or the sun. Recommend that the client say out of the sun or sun tanning booth for at least twenty-four hours after treatment if photosensitizing essential oils were applied to the skin.

3. Avoid prolonged use of the same essential oils.

4. Avoid the use of essential oils you know nothing about on your clients. Research and get to know the oil prior to using it on others.

5. Avoid the use of undiluted essential oils on the skin, unless otherwise indicated.

6. If you suspect your client may be sensitive to specific essential oils or if your client has known allergies or sensitivities, it may be wise to perform a skin patch test.

7. Know the safety data on each essential oil and place into context of use and knowledge.

8. Use caution when treating a female client who suspects she is pregnant or has been trying to become pregnant.

9. Keep essential oils away from the eyes.

10. Essential oils are highly flammable substances and should be kept away from direct contact
with flames, such as candles, fire, matches, cigarettes, and gas cookers.

11. Make sure your treatment room has good ventilation.

12. Do not use essential oils internally unless trained to do so.

Safety Measures

1. 1. According to Schnaubelt, “if essential oils droplets accidentally get into the eye (or eyes) a cotton cloth or similar should be imbued with a fatty oil, such as olive or sesame, and carefully swiped over the closed lid.” With that said, I have found that flushing the eye with cold water is exceptionally helpful and it is what is recommended on a material safety data sheet.

2. If an essential oil causes dermal irritation, apply a small amount of vegetable oil or cream to the area affected.

3. According to Buckle, if a child appears to have drunk several spoonfuls of essential oil, contact the nearest poison control unit (often listed in the front of a telephone directory). Keep the bottle for identification and encourage the child to drink whole or 2% milk. Do not try to induce vomiting.

REMINDER:

Dosage safety

The dosage you choose to use for any given formulation depends on:

• The constitution of the client
• The condition being treated, and whether it is in an acute or chronic state
• The method of application (internal, cutaneous, diffusion, etc.)
• The safety information of each essential oil to be used, the experience and confidence of the practitioner, and established guidelines when applicable
• The integrity of the skin, if administered via the cutaneous route
• The age of the client or patient who will be using the formulation
• The specific goal of treatment
• The medication an individual is taking
• The knowledge and confidence of the practitioner
• The current commonly or generally accepted dosage

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