Allergic Contact Dermatitis is a localized inflammation of the skin. Allergy is the term given to a reaction by a small number of people to a substance (known as the allergen) which is harmless to those who are not allergic to it. Only small quantities of allergen are necessary to induce the reaction. In general, inflammation refers to a condition in the body when it is trying to react to a localized injury of tissues. Allergic symptoms usually occur within about 30 minutes after exposure. After contact with this substance that is normally quite harmless for most people, inflammation occurs. Another kind of contact dermatitis, allergic contact dermatitis, is different because it is an allergic response to skin contact with some allergy-causing material. Adults are affected by allergic contact dermatitis more than young children or the elderly.
Allergic contact dermatitis is not usually caused by things like acid, alkali, solvent, strong soap or detergent. These harsh compounds, which can produce a reaction on anyone's skin, are known as 'irritants'. Irritants cause approximately 80 per cent of cases of contact dermatitis. An irritant reaction is caused by the direct effect of an irritant substance on the skin. Among other changes, some substances can remove skin oils and moisture from the outer layer of the skin. This reduces the protective action of the skin and increases the ability of irritants to enter or infiltrate the skin.
In initial (acute) severe cases such as poison ivy, the skin gets red, itchy, swollen, and develops tiny blisters, which may break and leave crusts and scales. The skin becomes thick, red, and scaly with long-term (chronic) exposure to an allergen. The inflammation is confined to the area that had contact with the irritant, commonly the hands or face, but can occur on any part of the body.
Antihistamines are used to relieve the itching associated with contact dermatitis. Sedative antihistamines such as diphenhydramine and hydroxyzine can be taken at night to help patients sleep.
Avoid any substances that you know irritate your skin or trigger an allergic reaction. In some cases, washing thoroughly with soap and water after contacting a substance, such as a poisonous plant, can prevent or minimize symptoms.
Topical corticosteroid medications may reduce inflammation. Carefully adhere to instructions when using topical steroids because overuse of these medications, even low-strength over-the-counter topical steroids, may cause a troublesome skin condition. In severe cases, systemic corticosteroids may be needed to reduce inflammation.