General Toxicology Information

CHEMISTRY AND TOXICOLOGY

An essential oil may contain anywhere from 50 to thousands of different chemical constituents. This chemical diversity creates several unique characteristics.

Resistance phenomenon: Many invading organisms, viruses and bacteria, can adapt over time to synthetic chemical-based drugs. Because they contain a simple chemical make-up, antibiotics are relatively easy for an organism to adapt to. If they are able to adapt and become immune, the antibiotic then becomes ineffective for subsequent treatment. In time, organisms adapt so well that they no longer respond to antibiotic treatment. Science must then come up with a new, stronger chemical to fight this super resistant organism. This ability of organisms to adapt to drugs is called “resistance phenomenon."

Because essential oils contain so many diverse chemicals, bacteria and organisms can not adapt to them. Virtually no resistance phenomena have been reported for any of the oils, according to experts in the field.  Because the oils are a product of nature, always changing with each new distillation, there is practically no possibility that resistance phenomenon will ever be encountered. To read more about resistance phenomenon and essential oils, read Healing with Essential Oils and Medical Aromatherapy by Kurt Schnaubelt.

Feedback loops: By isolating one chemical as is done in the production of drugs, scientists can more easily study the effects of that chemical on the human body. Through controlled studies, it is possible to determine how a chemical will affect a large percentage of the population. Because a synthetic drug has only one main action on the body, there are no balancing actions provided. Dosage becomes very important and chances for side effects are high. For more information on feedback loops, read Medical Aromatherapy by Kurt Schnaubelt.

Essential oils contain hundreds or thousands of chemicals acting at once. This opens the potential of forming feedback loops with the body. For example, when a sedative oil is applied, components are available that are relaxing or sedating. At the same time, there are trace amounts of stimulating components as well. This means the body can use the sedative components of the oil, and when it begins to move out of balance with that property, the stimulating components can be used to create balance again. A feedback loop is created within the nervous system and the body may use what it needs when it needs it. This is part of the reason behind the fact that different people experience the same oil in a different way. For example-many people feel that geranium is a tissue regenerating oil, whereas others may believe it is a stimulating oil, and still others classify it as a relaxing oil. They are all “right”! Each person is responding to a different part of the chemical constituency, based on their body's individual needs.

Low toxicity: Because of the synergy of many different chemicals, often in trace amounts, essential oils can have a potent effect on the body in very low dosages. This means that there is a low potential for side effects compared to synthetic drug treatment. When essential oils are used topically and at proper dilution rates, undesirable effects are practically non-existent. Negative reactions are most often caused by deliberate abuse, such as trying to use essential oils to induce abortion, or by gross overdosing of essential oils.

 

CHEMISTRY AND TOXICOLOGY

Possible undesirable effects of the constituents within essential oils can include:

  • Liver or kidney toxicity
  • Seizures, neurotoxic effect
  • Allergic reaction, sensitization
  • Phototoxic effect
  • Abortifacient effect
  • Carcinogenic effect
  • Skin irritation


The major chemical families of potentially toxic essential oil constituents are the following:
 

KETONES:
 

  • Beneficial properties: Dissolve mucus, dissolve fats, stimulate tissue growth  and regeneration, healing to skin and tissues.
     
  • Possible toxic effects: Neurotoxicity, seizures, abortive, liver damage.
     
  • Safe use: Use with caution, always dilute, blend with other oils, use over a short time period. Avoid use during pregnancy and lactation, with small children, with epilepsy or seizures, with liver disease. Avoid using oils with very high amounts of ketones.
     
  • Very high-Avoid use:    Rue      Santolina      Mugwort      Boldo

  • High-Use with caution, high dilution rate, low doses, short duration:  Thuja Wormwood      Hyssop      Pennyroyal      Crested lavender      Horseradish

  • Moderate-Use with awareness, blend with other oils, dilute:  Spike lavender White camphor      Sage Wintergreen

  • Low-Minimal danger of toxicity:    Yarrow      Rosemary camphor chemotype Peppermint      Eucalyptus dives and E. polybractea      Atlas cedarwood

  • Very low-Contain ketones, considered non-toxic:    Everlasting      Eucalyptus globulus      Rosemary cineole and verbenon chemotypes      Vetiver


PHENOLS:
 

  • Beneficial properties: Strong antibacterial and antiseptic, counter irritant, highly oxygenating, stimulating, anti-oxidant properties
  • Possible toxic effects: Skin irritation, liver toxicity, shortness of breath, itching or burning
     
  • Safe use: Blend with other oils for topical application, always dilute, use internally short term usage (2-4 days) at moderate dosage, or use homeopathic dosage. Avoid use with asthmatics, skin sensitive individuals, during pregnancy, lactation, and with small children. Avoid undiluted topical use.
     
  • These oils contain significant phenol constituents:    Anise      Ajowan      Allspice      Basil      Bay leaf      Clove      Cassia      Oregano      Sassafrass      Savory      Tarragon      Thyme
     


SESQUITERPENES AND MONOTERPENES:
 

  • Beneficial properties: Anti-inflammative, pain killers, discharge toxins from glands and organs, oxygenate pineal and pituitary glands, antiviral, antibacterial, inhibit accumulation of toxicity in tissues, antidepressant, stimulating.
  • Possible toxic effects: Skin irritation, sensitization, rash or burning, photo sensitivity.
  • Safe use: Always dilute, use in low doses. Do not use within 24 hours before sun exposure or UV light exposure. Avoid use with highly sensitive or allergic individuals, small children.
  • These oils contain significant amounts of terpene constituents:  Clove      Cinnamon      Cassia      Juniper      Pine      Fir      All citrus oils

 

COUMARIN OR FUROCOUMARIN:
 

  • Beneficial properties: Synergistic-enhance the properties of other oils, circulatory stimulant, vein tonic, antispasmodic, sedative, bactericidal, fresh and stimulating aroma.
  • Possible toxic effects: Increases the body’s sensitivity; rashes, burning sensation, increased sunburn sensitivity (phototoxic).
     
  • Safe use: Avoid sunlight or UV light exposure within 24 hours of use.
     
  • These oils contain significant amounts of coumarin or furocoumarin constituents:    Angelica      Bergamot        Celery     Cumin      Grapefruit      Khella      Lavender      Lemon      Lemon verbena      Mandarin      Orange Parsley      Tagetes      Tangerine      Tarragon      All citrus      All absolutes
     

TOXIC OILS-General usage
 

  • Avoid using these oils, or wait until you have over 1,000 hours of aromatherapy experience. They are considerably toxic, and other oils can do the job more safely:     Bitter almond      Boldo     Buchu     Camphor     Calamus      Elecampane      Goosefoot      Horseradish     Jaborandi     Mugwort      Mustard      Rue      Santolina      Sassafrass     Tonka bean      Thuja      Turpentine      Wormwood

 

TOXIC OILS-Oral usage
 

  • Avoid using these oils orally. They are mildly to extremely toxic. When in doubt about the safety of an oil, use homeopathic doses for internal use. All oils listed above, plus:     Arnica      Ajowan      Birch      Cade      Hyssop Tagetes      Tansy      Wintergreen 
     
     

SAFEST OILS:
 

  • These oils are generally regarded as safe. They are the most benign oils, safest for use during pregnancy and for sensitive individuals:    Bergamot Chamomile      Champaca      Frankincense      Geranium      Lavender  Lemon      Mandarin      Marjoram      May chang      Myrrh      Neroli      Nerolina      Orange      Palmarosa      Patchouli      Rosemary-verbenon ct.      Rosalina      Rose      Tea tree      Ylang ylang      Jasmine abs.
  • Special considerations for pregnancy-even though an oil may be on the safe list, pregnant women can become very sensitive to aromas, and may have a reaction to the aroma of an oil. Always dilute to 1-2% for use during pregnancy. Fennel, dill and anise increase milk production during lactation, parsley and sage reduce milk production.
     


BABIES AND SMALL CHILDREN:
 

  • Unless diluted to a homeopathic dosage, avoid use of peppermint; it is too cooling for small children and can shock their systems. Avoid all toxic oils and oils that would not be used for sensitive individuals. Dilute to 1% or weaker. These oils are considered safe for babies and small children when used at low doses:     Bergamot      Chamomile      Frankincense      Geranium      Lavender      Lemon      Mandarin      May chang      Myrrh      Orange Palmarosa      Rosalina      Rose      Tea tree      Ylang ylang

 

SPECIFIC CONTRAINDICATIONS

Specific Symptom: Avoid these oils

Allergies:  Goldenrod

Asthma:  Yarrow     Oregano     Rosemary     Cassia

Breast cancer*:  Anise     Cypress*     Sage*     Clary sage      Coriander*

Cancer:  Calamus      Basil      Sassafrass     Tarragon

Epilepsy or seizures:  (All high to moderate ketone content)  Hyssop    Sage           Nutmeg     Fennel     Anise

Glaucoma:   Thyme      Hyssop      Cypress     Tarragon

Taking coumadin or other blood-thinning drugs:   Lavender      Khella      Spike lavender      Bay laurel

High blood pressure:    Lemon      Hyssop      Rosemary

Hypo-thyroid condition:    Fennel

Pregnancy:    All oils with very high to moderate ketone content

Lactation:    Cypress     Peppermint      Sage (suppress milk production)

Skin allergies:    All oils high in phenols, monoterpenes and sesquiterpenes

Sun exposure, tanning:    All oils with coumarin, all absolutes, all citrus oils

Tumors*:    Fennel*      Anise*      Caraway*

Urinary infection:    Juniper leaf (Use juniper berry, grapefruit or tea tree instead)

Young children under age 5:    Eucalyptus      Peppermint      All high to moderate ketone or phenol content
 

*Tumors and breast cancer advisory is offered for you to help make an informed choice. These oils contain plant estrogen-like substances that many feel may contribute to an already high estrogen condition. An alternative group feels that these plant hormones are exactly what the body needs, providing a signal to the body to stop producing estrogen.