Essential oils are often obtained from the same plants used for herbal medicine. The method of extraction is quite different and so the constituents and properties of an essential oil can be quite different to the herbal tincture.

The essential oils module contains information on a similar range of topics to the herbal modules. The constituent profile of the oil is often more detailed. This is partly because the oils are quality checked against a spectroscopic signature to verify origin and purity.

Aromatherapy uses essential oils to affect the skin and also via transdermal absorption for their systemic effects. This is a route which is infrequently exploited in herbalism and in traditional medicine. Notable exceptions are the French Herbalist Messeguet who used hand and foot baths and the use of patches to supply nicotine over a lengthy period.

The Herbal Repository will permit comparison of the herbal and aromatherapy traditions which shoul lead to interesting new applications for herbal plants.