Alopecia areata (AA) is a common, usually patchy (round), nonscarring hair loss condition affecting any hair-bearing surface (scalp, beard, moustache, body hair).

It is the most common hair loss complaint in children; approximately 20% of patients with AA are children.

Usually, this type of sudden and patchy hair loss is called alopecia areata. Alopecia areata is an autoimmune condition in which hair loss is very unpredictable. This condition can be observed at any age or in any gender.

Early-onset AA form associated with greater severity, long duration, and family history of the disease and a late-onset form characterized by milder severity, shorter duration, and low family incidence.

The exact cause of AA is unknown, but is likely to be an interaction between genetic and environmental factors.

Most of the recent studies supports auto-immunity as the major pathogenic process in AA. AA can be seen as an autoimmune condition characterized by T cell–mediated attacks on the hair follicle. The inciting antigenic stimulus is unknown.