Aromatherapy is a term coined by French chemist René Maurice Gattefossé in the 1920's to describe the practice of using essential oils taken from plants, flowers, roots, seeds, etc., in healing. It has lead to a lot of New Age nonsense. The healing power of essential oils is the main attraction in aromatherapy. There is very little evidence for all the claims made by aromatherapists regarding the various healing properties of oils. Most of the support for the healing power of such substances as tea tree oil is in the form of anecdotes. A lot of that is based on good old post hoc reasoning, i.e. I rubbed some peppermint oil on my sore knee when I boarded the airplane for Chicago and when I got there the pain was gone. The aromatherapists generally do not allow testing or science to invade their province. There are no scientific studies. When we look at what people who call themselves aromatherapists claim, we must conclude that aromatherapy is a mostly a pseudoscientific alternative medical therapy. It is a mixture of folklore, trial and error, anecdote, testimonial, New Age spiritualism and fantasy. What aromatherapy lacks is a knack for sniffing out non-sense. I would not reject aromatherapy out of hand, however. When I have a cold and a stuffy nose, I'll use Vicks VapoRub, a mixture of camphor, menthol and eucalyptus oil. Strictly speaking, I suppose I am a practicing aromatherapist.

At best it's soothing and at worst it's benign and harmless.