The earlier hair loss begins, the greater the eventual loss. Some persons have short periods of intense hair loss, followed by long, stable periods. In men, hair loss occurs on top of the head and in the temple areas of the scalp. In women, hair loss usually occurs only on top of the head. In both sexes, some diffuse loss may also occur.
Male hormones are an important factor in balding.
Hair loss that occurs after illness, pregnancy or as an adverse reaction to drugs is a different form of baldness. The drug minoxidil has been shown to slow or reverse baldness to some degree in some men. Other medical treatments are undergoing study. Your own observation of symptoms. Medical history and physical exam by a doctor, if diagnosis is in doubt.