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If you’ve ever used essential oil aromatherapy to get rid of your headache, calm an upset stomach or clear up a case of athlete's foot, then you are well aware of the many potential health benefits they provide. The same properties and ability to positively influence your health and well being can also have negative effects on your body. Aromatherapy is not a hobby to experiment in without consequence, so before using essential oil aromatherapy, learn about the potential negative effects certain oils and treatment methods have.


Even natural substances like essential oils can be toxic. There are many essential oils that should never be used in aromatherapy because they are potentially toxic. Aromatherapist and author Patricia Davis writes in her book, “Aromatherapy: An A-Z” that toxic oils can cause damage to your liver, kidneys and nervous system. Toxic effects are exacerbated if you take the oils internally. According to the University of Maryland Medical Center, taking a toxic oil by mouth is potentially fatal. Davis writes some oils to avoid because of toxicity include: camphor, mugwart, thuja, wintergreen, sage, thyme and eucalyptus.


Some essential oils used in aromatherapy produce a negative side effect from prolonged direct sun exposure. Julie Lawless, aromatherapist and author writes in her book, “The Illustrated Encyclopedia of Essential Oils” that you should not use oils like angelica root, bergamot, cumin, lemon or orange on any part of your body that is going to be exposed to the sun as you will easily get sunburn.

Skin Irritation

One of the most common negative side effects in aromatherapy is using oils that can cause skin irritation. Oils with skin irritant properties can cause rashes, itching and burning sensations. Patricia Davis writes that when practicing aromatherapy skin irritation is one of the most varied negative effects depending on how sensitive the person’s skin is. While there are some oils that should never be used on the skin, there are others such as peppermint and lemon, that can be used safely if diluted sufficiently. If you are using an essential oil in aromatherapy that may act as a skin irritant, be cautious and use the oil in a very low concentration--about 1 percent.