Safe Use of Essential Aromatherapy oils

Safe Use of Essential Aromatherapy Oils

It is very important when using essential oils for aromatherapy purposes to understand the contraindications. They need to be used properly and should never preclude seeing a doctor or health care provider if your condition warrants it.

Basically the use of essential oils, with few a exceptions, is quite safe. When used in excess they can cause allergic reactions or may cause irritation or burning sensations. However, the risks are few relative to conventional pharmaceuticals. Far more poisonings are reported for pharmaceuticals than plant based poisonings and most plant based poisonings are from ingesting house plants. That said, it is still best to be informed.


One of the most common of the toxic substances in essential oils are “ketones”. Not all ketones are toxic but some can be neuro-toxic (passing through the blood/brain barrier) in excess and may also cause liver damage. Essential aromatherapy oils with high ketone content do not need to be completely avoided but they do need to be used carefully.

Oils Containing High Ketone Levels

Rue (poisonous), Mugwort (poisionous),  Thuja (small doses only, used externally only), Wormwood, Hyssop (utmost caution), Pennyroyal (avoid excess, poisonous in large doses),  Crested Lavender (not for use with children)

Oils Containing Medium Ketone Levels

Sage (least toxic of oils containing the ketone Thujone), Spike Lavender (used with benign oils), Camphor (neurotoxic, induces abortion)

Oils Containing Low Ketone Levels

Yarrow (use with caution with children), Rosemary ( non-toxic in small doses), Peppermint (non-toxic in small doses, use care with small children), Eucalyptus ( non-toxic if mixed with other oils), Atlas Cedar (external use is non-toxic)


Oils containing phenols have been taken internally because they have very strong antibacterial qualities. Oregano is probably the most commonly used oil containing phenols. In the last 10 years or so it has become quite common in a capsule form on the shelf in your neighborhood healthfood store. At high doses, oils with phenols can cause liver damage…..they are safe when used in low dosages but even that should not be continued for long periods of time. Four to five days maximum for therapy with these types of oils.

Oils with Phenols

Oregano, Thyme, Clove leaf oil, Savory – most recommendations for the oils are internal… not take any essential aromatherapy oils internally without the advice of an informed practitioner. If you use these oils externally apply to the bottom of the feet mixed in a carrier oil (i.e jojoba).


Some oils can be highly irritating to the skin and can even burn the skin. The following are generally not recommended to be be applied to the skin, Clove leaf, Clove flower, Cinnamon, Cinnamon leaves, Cassia, Oregano, Thyme, Savory. I have personally applied Oregano oil that has been diluted in a carrier oil to the skin above swollen glands in my throat. It is very effective in reducing the swelling in the glands but one time I was in a hurry and applied it “neat” and it burned my neck! Thyme oil will kill a tick. I applied one drop of thyme oil to a tick that was on my dog and all the hair fell off an area about the size of a dime!  You can apply the oil to the back of the tick without getting it on the dog’s skin with a Q-tip, and the tick will die. So, you know this is strong!


NEVER apply essential oils to a cat. Their livers cannot handle it.


Abdominal pain – Clove, Cinnamon

Asthma – Marjoram, Oregano, Rosemary, Yarrow

Breast Cancer – Cypress, Angelica, Sage, Fennel, Caraway, Anise

Epilepsy – Anise, Fennel, Hyssop, Nutmeg, Parsley, Sage

Glaucoma – Thyme, Hyssop, Cypress, Tarragon

Hemorrhaging – do not use Lavender in combination with an anticoagulant

High Blood Pressure – Lemon, Hyssop

Hypothyroidism – Fennel

Insomnia – Peppermint, Pine

Mentrual complaints – Angelica, Anise, Caraway, Cypress,  Sage

Prostate Cancer – Angelica, Cypress, Hyssop, Thyme

Tumors – Anise, Caraway, Fennel

Urinary Tract Infection – Eucalyptus, Juniper


You may have reactions to some oils if you apply them to your skin and then go out into direct sunlight. Some of these oils are listed here.  Angelica, Bergamot, Celergy, Lavender, Lemon, Mandarin, Orange, Parsley, Tarragon


If you are wondering if some of these oils will work for you, you may always make a weak dilution, 3 drops to 1/2 oz. of carrier oil, and patch test it on your skin. If any rash or reaction occurs, don’t use it.

For further in-depth information please check out the books below which I referenced for the information you see here.

Advanced Aromatherapy: The Science of Essential Oil Therapy  by Kurt Schnaubelt, PhD

Aromatherapy Workbook by Marcel Lavabre

Aromatherapy Book: Inhalations and Applications (Jeanne Rose Herbal Library) by Jeanne Rose

375 Essential Oils and Hydrosols  by Jeanne Rose

Aromatherapy for Healing the Spirit: Restoring Emotional and Mental Balance with Essential Oils  by Gabriel Mojay

The Complete Guide to Aromatherapy  by Salvatore Battaglia

Encyclopedia of Essential Oils: The Complete Guide to The Use of Aromatic Oils In Aromatherapy, Herbalism, Health and Well Being   by Julia Lawless

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