Dermal Absorption of Essential Oils
Like most aromatherapists, I was taught that
essential oils penetrate the stratum corneum via the skin surface and then pass through the dermis, entering the general circulation. This is accepted as being the most important route for essential oils to work in aromatherapy and a full body massage is the usual way aromatherapy is administered, although the oils are also used in lotions, creams and other carrier media, compresses and baths for dermal absorption. Where a full body massage is not possible, a back massage is indicated because “the back presents the single largest expanse of skin of any body area” (Davis 1988 pp.218). According to Gattefossé (1937 p.62), who is considered to be the “Father of aromatherapy” as he coined the term ‘aromathérapie’, cutaneous absorption of volatile substances has been demonstrated physiologically and clinically and is better if the product is brought to body temperature. However, he did recommend that the skin is cleansed first with a solvent and that the substance is not too volatile as to dissipate into the air. It must also dissolve fats rapidly and he suggested they be dissolved in alcohol. Some drugs are now administered in the form of skin patches, and this is taught as being "conclusive evidence" that essential oils are freely absorbed in a similar manner; however according to Watt (1993) “even hormone patches require the solution of the hormones in alcohol or other solvents in order to permit their absorption by the skin”. Valnet (1980) on the other hand gives that, “The skin’s absorptiveness has always been exploited in the treatment of general conditions (e.g. with iodine paint or friction rubbing with liniments based on garlic, olive oil or camphor). The modern pharmacopoeia contains many ointments whose active principle (anti-coagulant or hormonal), is designed to have an effect on the whole body through rubbing on the skin” (Valnet (1980) p71). The “Mother of Aromatherapy” is a title affectionately given to Madame Marguerite Maury and in her book “Guide to Aromatherapy ”, first published in French in 1961 (p71), she surmised that essential oils penetrate the bloodstream via the capillaries and cites Dr Badmadjeff as the source of this information. It is through her research that we use massage in aromatherapy today as she had originally given her clients essences to inhale yet had found this to be a temporary and unsatisfactory form of treatment. Robert Tisserand explores Mme Maury’s work (1980 p71) and explains that cutaneous penetration of essences is slower, more diffuse and therefore safer than inhaling or indeed ingesting them. In the UK, aromatherapists do not administer essential oils internally as only a medically trained herbalist has the knowledge and training to prescribe this safely. All our work is done through cutaneous absorption and inhalation and it is sometimes proffered that internal ingestion means that essential oils are altered by chemical digestion/enzymes. However, Burfield T (2004) also states that metabolic changes of
absorbed essential oil components by enzymes within the dermis, may frequently occur. Another key figure in aromatherapy teachings, Dr. Jean Valnet, confirms that research existed at the time of writing his book that proved essences pass through the layers of skin to be rapidly circulated in the blood and eliminated by the lungs and kidneys. He cites studies carried out by Valette C. (1945) where oils
were used on rabbits (Valnet. (1980 p69). However, according to Watt (1993), “human skin is far less permeable than animal skin” and so this may not be an accurate representation of what occurs in aromatherapy on humans.
It follows that all the books written subsequently on aromatherapy have remained faithful to what has been written before and have published that essential oils are readily absorbed through the skin (P Davis 1988 p9, Ryman D. 1984 p 41, Lawless J. 1992 p.26, Price