skin disorders
Contact Dermatitis
Allergic contact dermatitis
This type of dermatitis is a reaction by the body's immune system to a substance contacting the skin. When the skin first comes into contact with the substance, the skin becomes sensitized to that substance. Sometimes a person can be sensitized by only one exposure, and other times sensitization occurs only after many exposures to a substance. After a person is sensitized, the next exposure causes intense itching and dermatitis within 4 to 24 hours, although some people, do not develop a reaction for 3 to 4 days. Thousands of substances can result in allergic contact dermatitis. The most common include substances found in Metals (such as nickel) Preservatives Plants (such as Poison Ivy ) Rubber (including latex) Fragrances Nickel sulfate is the most common contact allergen in most populations. It is a common component of jewelry. People may use (or be exposed to) substances for years without a problem, then suddenly develop an allergic reaction. Even ointments, creams, and lotions used to treat dermatitis can cause such a reaction. Sometimes allergic contact dermatitis results only after a person touches certain substances or ingests them and then exposes the skin to sunlight (photoallergic contact dermatitis—see Chemical photosensitivity ). With photoallergic dermatitis, the reaction may spread to areas of skin that were not exposed to the sun. Typical causes include fragrances (such as musk ambrette and sandalwood), antiseptics, NSAIDs, and sunscreens. Chemicals used in shoe or clothing manufacturing:Tanning agents in leather; rubber accelerators and antioxidants in gloves, shoes, undergarments, other apparel; dyes Cosmetics:Hair dyes, nail polish, nail polish remover, deodorants, moisturizers, aftershave lotions, perfumes, sunscreens Skin products whose ingredients contain medications:Antibiotics (bacitracin, sulfonamides,neomycin), antihistamines (diphenhydramine), pain relievers (benzocaine) Fragrances:Found in toiletries, soaps, and scented household products (such as detergent) Metals:Nickel, cobalt, chromates, mercury, gold Poison Ivy , poison oak, poison sumac Rubber (including latex):Gloves, condoms, catheters, balloons, shoes 