A dry, scaly, itchy eruption of the scalp; it may also occur, less commonly, as thick, greasy scales. Dandruff is also known as seborrheic dermatitis. It is thought to affect about 60 percent of people to some degree; the condition, although unsightly, is of little consequence. It is sometimes associated with blepharitis.
There are many shampoos on the market that are designed to relieve this common condition. If the dandruff is not responsive to the medicated shampoos and the condition is a troubling one, the person should seek advice from a physician. There are prescription medications available, including a selenium shampoo, that may be of help.