When aromatherapy is used for the treatment or prevention of disease, a precise knowledge of the bioactivity and synergy of the essential oils used, knowledge of the dosage and duration of application, as well as, naturally, a medical diagnosis, are required. In the Anglo-Saxon world, even among "natural" practitioners like herbalists or naturopaths, aromatherapy is regarded more as an art form than a valid healing science. At best, it is viewed as a complementary and seldom the only treatment prescribed.

On the continent, especially in France, where it originated, aromatherapy is incorporated into mainstream medicine. There, the use of the anti-septic properties of oils in the control of infections is emphasized over the more "touchy feely" approaches familiar to English speakers. In France some essential oils are regulated as prescription drugs, and thus administered by a physician. In many countries they are included in the national pharmacopeia, but up to the present moment aromatherapy as science has never been recognized as a valid branch of medicine in the United States, Russia or Germany.

Essential oils, phytoncides and other natural VOCs work in different ways. At the scent level they activate the limbic system and emotional centers of the brain. When applied to the skin in the form of massage oils they activate thermal receptors, and kill microbes and fungi.

Internal application of essential oil preparations, mainly in pharmacological drugs, may stimulate the immune system, urine secretion, may have antiseptic activity etc. Different essential oils have very different activity.; they are studied in pharmacology and aromachology.

While the practice of aromatherapy is sometimes thought to be confined to inhalation, it may include various methods, including:

* Inhalation (directly or diffused into the air)

* Absorption through the skin (baths, massages, compresses)

* Absorption through the mucous membranes (oral rinses and gargles)

* Ingestion (occasionally prescribed, with caveats)

Skeptics argue that while pleasant scents can be relaxing, lowering stress and related effects, there is currently insufficient scientific proof of the effectiveness of aromatherapy. Like many alternative therapies, few controlled, double-blind studies have been carried out. A common explanation is that there is little incentive to do so if the results of the studies are not patentable.

There are some treatments generally accepted in Western medicine to give a form of relief for the airways in case of cold or flu, such as mint and eucalyptus essential oils.

Some skeptics acknowledge that aromatherapy has limited scientific support but argue that its claims go beyond the data or that the studies are not adequately controlled and peer reviewed.

The term "aromatherapy" has been applied to such a wide range of products that almost anything which contains essential oils is likely to be called an "aromatherapy product", rendering the term somewhat meaningless in that context.

Some proponents of aromatherapy believe that the claimed effect of each type of oil is not caused by the chemicals in the oil interacting with the senses, but that the oil contains a distillation of the "life force" of the plant from which it is derived that will "balance the energies" of the body and promote healing or well-being by purging negative vibrations from the body's energy field.

Arguing that there is little scientific evidence that healing can be achieved, or that the claimed "energies" even exist, many skeptics reject this form of aromatherapy as pseudoscience or even quackery.

Disclaimer: The information presented here should not be interpreted as or substituted for medical advice. Please talk to a qualified professional for more information about aromatherapy.