The latest fashion statement for teens is to dye their hair outrageous colors. But they may be getting more than they bargained for: Facial swelling and an itchy, flaking rash resembling poison-oak can develop on the face or scalp. This rash, called contact dermatitis, is a result of the immune system reacting to phenylenediamine, a chemical commonly found in hair dyes. Despite what the accompanying article states, anaphylaxis (which is most often caused by allergic antibodies) does not occur as a result of contact dermatitis to hair dye.
Contact dermatitis can also occur to many other chemicals used on the body, including cosmetics, toothpaste, shampoos and even sunscreens. Usually, the resultant rash occurs on the area of skin where the substance was applied, but may occur first on more susceptible skin - such as the neck and eyelids.