Allergic contact dermatitis develops when the body reacts to an allergen that touches the skin, according to the American Academy of Dermatology. In contrast to irritant dermatitis, which is caused by harsh chemicals or other irritants touching the skin, allergic contact dermatitis is typically caused by things that would normally not cause a reaction in people who are not susceptible to that particular allergen.
Symptoms
The skin becomes red and inflamed when brought into contact with the allergen. Sometimes, itching may develop. The skin may feel tender, swollen, warm to the touch or may develop rashes or lesions. A rash caused by allergic contact dermatitis may have small blisters associated with it, explains Merck. Only the area actually contacted by the allergen will develop symptoms, but allergens can be carried on clothes or transferred from the hands to the face or anywhere else the person touches. Once the allergen is washed off, further spread cannot occur, although in thicker areas of skin, the reaction may take longer to develop, giving the illusion that it was not present there originally. Most symptoms appear within 4 to 24 hours, but in some cases, it can take up to 4 days to see the characteristic skin rash.
Causes
Many things may cause allergic contact dermatitis. Plants such as poison ivy or poison oak are a frequent culprit. Nickel in jewelry or watches may cause a reaction in some people. Other people have allergies to latex, cosmetics, fragrances, detergents and some medications. Sometimes, the allergic reaction is delayed until exposure to sun takes place, which is often the case with allergies to sunscreen, shaving lotions and some perfumes, explains MedlinePlus.
Treatment
The first stage of treatment is to remove the allergen from the skin through washing or rinsing the affected area, explains MedlinePlus. Corticosteroids in cream form slow inflammation, and oral corticosteroids may help treat severe allergic reactions. Without treatment, allergic contact dermatitis lasts about 2 to 3 weeks.
Prevention
Preventing allergic contact dermatitis mainly involves avoiding contact with known allergens. If exposure does occur, washing the area of skin that touched the allergen may be able to prevent a full-blown allergic reaction. In some cases, the specific allergen must be identified through a skin test or through observation before it can be avoided. Individuals allergic to something they cannot avoid, such as something at work, can use protective clothing to avoid getting these substances on the skin.
Complications
Most of the time, allergic contact dermatitis causes no permanent problems, only short-term pain and discomfort. In some cases, however, scratching the affected area can lead to bacterial infection or permanent scarring. A condition called neurodermatitis, in which patches of skin become leathery and tough, can also develop from the itching caused by allergic contact dermatitis, according to MayoClinic.com.
