Alopecia areata is a condition in which a person has hair loss as a result of the immune system attacking the hair follicles. We do not know why this happens. Often, the hair loss involves only a few patches, which are round in shape. Hair loss is usually seen on the scalp, face or body, but is most common on the scalp. Sometimes it can be more extensive.
About 4 million people in the United States have alopecia. It affects people of both sexes, all ethnic backgrounds and can occur at any age. It is only rarely seen with other autoimmune diseases in children. Alopecia areata often happens once and then there is regrowth of normal hair. Sometimes, recurrent episodes of hair loss may occur with periods of regrowth. This may occur over many years.
- Alopecia areata − patches of hair loss, usually in the scalp
- Alopecia totalis − complete loss of scalp hair
- Alopecia universalis − complete loss of hair on the head, face and body (may occur very rapidly)