A contact allergen is a substance that can cause allergic reactions in people upon contact with skin. Such reactions may include itching, redness, swelling, rashes, or even anaphylactic shock.
Contact allergens can be a variety of substances, such as metals (eg, nickel), plants (eg, poison ivy), cosmetics (eg, creams, shampoos), drugs (eg, antibiotics), chemicals (eg, dyes), and a lot others.
Often contact allergens cause allergic reactions only in people who have had contact with these substances in the past. The first exposure may not cause a reaction, but upon repeated exposure to the allergen, a person may develop sensitivity and begin to react to it with allergic symptoms.
Various methods are used to diagnose contact allergen allergies, including skin tests and blood tests. Treatment for contact allergies may include avoiding contact with the allergen, using ointments and creams, antihistamines, and glucocorticosteroid injections.
It is important to remember that allergy to a contact allergen can be a serious condition and you should seek medical help at the first onset of allergic symptoms.