Allergic contact dermatitis is caused by a reaction to substances called allergens that come into contact with your skin. In susceptible people, these contact allergens can cause itching, redness, and blisters that is known as allergic contact dermatitis.
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. Later the skin may darken and become leathery and cracked. Allergic contact dermatitis can be difficult to distinguish from other rashes.
Careful review of the materials that your skin encounters everyday and at work is helpful in identifying the allergen. Most contact dermatitis is diagnosed by distribution of the rash. Sometimes the cause cannot be identified by history or physical examination and you may need PATCH TESTING.
Patch tests are a safe and easy way to diagnose contact allergies. Patch tests are different from injection or scratch skin tests because they test for different allergens. In patch tests, small amounts of the possible common allergens are applied to the skin on strips of tape and then removed after two days. A positive allergy test shows up as a small red spot at the site of the patch.
Common allergens include nickel, rubber, dyes, preservatives, medications, fragrances, poison ivy, poison oak, and related plants.
Mild rashes that occur from allergic contact dermatitis usually respond to topical steroid creams and/or oral antihistamines that your dermatologist will prescribe. It may also be necessary to apply moist compresses to blistered areas for a few days and keep these areas covered.
Severe rashes may need to be treated with systemic methods such as oral and injectable corticosterioids, antibiotics, or other anti-inflammatory and immunologic agents.
People with allergic contact dermatitis should:
Avoid the allergen that causes the reaction and chemicals that cross-react with it. Your dermatologist can help you identify items
Substitute products that do not cause reactions. Your dermatologist can suggest sources for these products.