Neat application and internal use
Generally, the application of undiluted essential oils directly to the skin should be avoided as many are highly irritant. However, there are one or two exceptions which have been safely applied to the skin undiluted for centuries. These include lemon oil, which can be applied neat to warts (Vaseline can be applied around the wart to protect the surrounding skin); lavender, which can be safely applied directly to burns, cuts, bites and stings; and tea tree, which may be dabbed on spots.
Any other oils must be used in dilution unless under careful direction from a trained aromatherapist. Many essential oils are highly toxic when taken orally and there are no circumstances in which they may safely be taken at home in this way.
Mode of action of essential oils
Although the subject of a great deal or research, there is a lack of knowledge about how essential oils work in the body to produce their therapeutic effects. It is known that individual essential oils posses antiseptic, antibiotic, sedative, tonic and stimulating properties, and it is believed that they act in harmony with the natural defences of the body such as the immune system. Some oils, such as eucalyptus and rosemary, act as natural decongestants whereas others, such as sage, have a beneficial effect upon the circulation.