Allergic Contact Dermatitis

Allergic contact dermatitis (ACD) is a very common problem affecting millions of people yearly. This condition occurs when the skin reacts to allergens it comes into direct contact with.

What causes ACD?

Not everyone develops ACD. Only some individuals who are genetically predisposed do develop ACD. When such an individual becomes exposed to an offending allergen, the clinical disease of ACD becomes manifest.

How can we avoid getting ACD?

The most important way to avoid ACD is to avoid the offending allergens.

Are laboratory tests necessary?

Clinical evaluation, including a comprehensive history and physical examination, is usually enough to establish presence of an allergic skin reaction. No specific laboratory tests are necessary for allergic reactions, although a doctor may request some tests in order to determine the cause of the skin rash. Some of these tests include:

• Scratch tests, also called prick tests or puncture tests. In these tests, the dermatologist applies test solutions of possible allergens to scratches or shallow punctures on the skin.
• Intracutaneous tests, in which the physician injects the allergen into the skin, are often necessary when percutaneous tests (on the surface of the skin) are unclear.
• Patch test, which is not an “immediate-type reaction” test like the percutaneous test. After the dermatologist applies the patch containing samples of allergens to the patient’s back, the patient must come back in 48 hours (and, in some cases, once more after 72 and/or 96 hours) so the dermatologist can see the patient’s reaction to the allergens.

How are allergic reactions treated?

The best treatment for ACD is the removal of the cause. To that end, identification of the offending agent is very important. In acute cases of allergic reactions, H1-type antihistamine drugs are the first choice in their management.

Apart from avoidance of allergens and medication, another important component in management of allergic skin reactions is patient education. Individuals must learn what substances to avoid and what to do during allergic attacks. Potentially life-threatening attacks can be avoided with proper education.