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Some essential oils contain more active chemical components than others; this makes some essential oils either unsuitable for aromatherapy use, or only suitable for use with caution.

The Safe Use of Essential Oils

Essential oils are composed of many different chemical components that give an essential oil the ability to treat certain health conditions.  However, the chemical components of some essential oils can, in some instances, adversely affect the reaction of an essential oil.  Although many essential oils can be used safely, it takes knowledge, control and correct usage.

Some essential oils are not advised for therapeutic use in aromatherapy at all because of the high content of  active chemical components.  In addition, there are other essential oils which are safe for use under normal circumstances but are not advised for use with babies, young children or in pregnancy.
Adverse Effects of Essential Oils

The chemical make-up and constituents of some essential oils can effects such as:

–skin sensitivity/irritation
–be carcinogenic
–liver toxicity

Essential oils, even in a pure and unadulterated state, can cause harm because of the volatile ingredients that it contains.  It is very important to correctly identify an essential oil and know any potential adverse effects; in addition, an essential oil that is extracted from a plant may be chemically different to the plant in its natural state.  Therefore, some plants used in plant medicine may be harmless but, in essential oil form, may be dangerous.

Essential Oils to Avoid in Aromatherapy Use

There are many essential oils that are distilled from plants but are not suitable for aromatherapy use; the following list is not intended to be a complete and absolute list of unsuitable essential oils for therapeutic purposes, but an example of essential oils that may be potentially dangerous.

Essential Oils Not Recommended for Aromatherapy Use (A - R)

The following essential oils are not recommended for therapeutic use in aromatherapy:

–Ajowan (Trachyspermum copticum) – dermal irritant; high thymol content
–Arnica (Arnica montana) – highly toxic; do not confuse with Arnica tincture which is different
–Bitter Almond (Prunus dulcis var. amara) – contains the poison prussic acid (cyanide)
–Calamus (Acorus calamus var. angustatus) – possible carcinogenic effects
– Cassia (Cinnamomum cassia) – dermal toxin, sensitizes and irritant
–Chevril (Anthriscus cerefolium) – possible carcinogenic effects
–Costus (Saussurea costus) – extreme dermal sensitivity
–Deertongue (Carphephorus odoratissimus) – liver toxicity; possible dermal and phototoxic risk due to lactone content
–Dwarf Pine (Pinus mugo var. pumilio) – sensitizes and dermal irritant
–Horseradish (Armoracia rusticana) – both a dermal irritant and oral toxin
–Jarborandi (Pilocarpus jaborandi) – abortifacient, skin irritant and oral toxin
–Mugwort (Artemisia vulgaris) – oral toxin due to high thujone content; abortifacient
–Mustard (Brassica nigra) – extremely toxic in oral and dermal
–Orris (Iris pallida) – often adulterated; the fresh roots cause sickness in large doses.  Do not confuse with orris powder
–Pennyroyal (Mentha pulegium) – oral toxin and abortifacient due to pulegone content.  Large quantities may cause death
–Rue (Ruta graveolens) – contains methyl nonyl ketone; oral toxin, abortifacient and skin irritant.

Essential Oils Not Suitable for Therapeutic Purposes in Aromatherapy (S - Z)

–Santolina (Santolina chamaecyparrisus) – oral toxin
–Sassafras (Sassafras albidum) – extremely toxic; carcinogenic, irritant and abortifacient
–Spanish Broom (Spartium junceum) – toxic; contains the component sparteine
–Spanish Oregano (Thymus capitatus) – skin irritant and dermal toxin
–Summer Savory (Satureja hortensis) and Winter Savory (Satureja montana) – dermal toxin and irritant
–Sweet Birch (Betula lenta) – harmful due to menthyl salicylate content
–Tansy (Tanacetum vulgare) – oral toxin and abortifacient ; high thujone content
–Tonka (Dipteryx odorata) – oral and dermal toxin; high coumarin content
–Thuja (Thuja occidentalis) – abortifacient and oral toxin; high thujone content
–Wintergreen (Gaultheria procumbens) – irritant, toxic and sensitizing
–Wormwood (Artemisia absinthium) – toxic and an abortifacient

Factors Affecting the Use of Essential Oils in Aromatherapy

The essential oils mentioned in this article are not a complete guide to dangerous or unsuitable essential oils for therapeutic purposes in aromatherapy; assess each individual circumstance as to the dangers associated with the use of a particular essential oil and/or take professional advice.  With reference to oral toxicity, some practices of aromatherapy, particularly in Europe, administer essential oils orally; this is not a recognized practice in the United States and, in any circumstances, should never be attempted without professional advice.

However essential oils are used and in whatever circumstances, it should be noted that all the essential oils listed in this article have active chemical components that make them, in general,  unsuitable essential oils for therapeutic use in aromatherapy.


- Lawless, Julia 1995 The Illustrated Encyclopedia of Essential Oils UK:Thorsons
- Schnaubelt, Kurt 1998 Advanced Aromatherapy: The Science of Essential Oil Therapy USA: Healing Arts Press

This article was written by Sharon Falsetto and appeared in its original format on Suite101 as Essential Oils Not Suitable for Aromatherapy Use

It is expressively prohibited to copy or use this article in any way unless written permission is given by the author Sharon Falsetto.  If it is discovered that copyright laws have not been complied with, legal action will be pursued by the author Sharon Falsetto.

CopyrightSharonFalsetto2010 All Rights Reserved
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