Histamine is a product of the breakdown of protein, which is thought to occur in the living body only when tissues are damaged. Histamine is released, and one of its actions is to cause dilation of the small blood vessels in the immediate area, giving rise to redness and heat. Fluid may seep out of the dilated capillaries inTo the surrounding tissues, causing swelling and irritation. Other actions of histamine include stimulation of the stomach and intestines, and contraction of the bronchi, leading to asthma attacks. The release of histamine is a normal defence mechanism, and discomfort is only experienced if too much is produced. Histamine may be released in response to an attack on the body in the form of a sting from nettles or insects, and as histamine is also present in the poisons manufactured by the plant or insect, an excess of it can very quickly build up in the area immediately surrounding the sting. It may also be released — sometimes in very large amounts -in response to inhaling pollens, animal hair and many other irritant substances, giving rise to the acute discomfort of hay-fever.

The orthodox medical approach is to treat with anti-histamine drugs. The anti-histamines are chemically similar to histamine, but do not provoke the same responses in the body.

The aromatherapist's response will be to select one of several calming and soothing essential oils, Camomile and Melissa being the most important, and apply them in various ways, which will depend on whether the problem is a skin irritation, or a respiratory disturbance such as asthma or hayfever. In the case of insect stings, direct application of oil of Lavender or oil of Lemon as soon as possible after the sting has hapened, will often prevent the local reaction of itching and swelling, suggesting that these oils may have an anti-histamine effect.

Inhalations of Camomile, Melissa, Lavender, Hyssop, Benzoin or other oils found to help the individual, can give effective symptomatic relief to hayfever and asthma sufferers, but in the long term it is important to use massage, baths and possibly dietary advice to try to lessen the individual's response to such stimuli as pollens, animal hair, certain dusts and other irritants.

Nobody yet understands fully the role of histamine in allergic reactions. In some instances the body produces a flood of histamine in response to a relatively minor threat, and in others it will produce histamine when there is no external threat at all. Without yet knowing why, we do know that stress plays a very big part in allergic reactions. People who are under stress will often react to a substance that causes no problems when the same person is in a stress-free state.

The aromatherapist's approach to allergy involves looking beyond the immediate symptom and trying to alleviate the underlying stress. All the oils listed above have a calming and soothing effect on the mind and the emotions, and in many cases will help the allergy sufferer to reach a state of balance where the external irritant no longer provokes an abnormal flood of histamine into the body.

See also ALLERGIES.