Baldness is the partial or total absence of hair on the scalp. Some thinning of the scalp hair takes place as a normal part of the process of aging. However, many types of abnormal hair loss also occur.
Some kinds of baldness involve only a thinning of the hair or a loss of hair from one small area of the scalp. But in the most common type, called male pattern baldness, a man loses much or all of the hair over the top of the head. A smaller number of women have a condition known as female pattern baldness. This condition involves thinning of the hair but usually not complete baldness and begins later in life.
A healthy scalp sheds old hairs continually, and new ones grow to replace them. Baldness develops when new hair stops growing for any reason. In male pattern baldness, hair loss results from the combination of an inherited trait and the effects of the hormone testosterone. Loss of hair may begin during the teen-age years or at any later time.
Pattern baldness cannot be cured. However, many types of baldness are temporary, and normal hair growth can be restored in many cases. Temporary baldness may be a symptom of many serious illnesses, of a skin infection, or of emotional stress. The use of certain drugs may also cause temporary baldness.
In male pattern baldness, heredity strongly influences the degree of hair loss and the age at which it begins. A man can inherit baldness from either his father or his mother. The exact pattern of inheritance is not known. The percentage of men who have male pattern baldness increases with age.
People may use any of several methods to cover bald areas. Many wear a hairpiece, such as a toupee or a wig. Others prefer hair weaving, a technique in which the sides of a hairpiece are sewed into the remaining hair. In a process called hair transplanting, a doctor surgically removes plugs of the scalp that contain growing hair. The plugs are then transplanted to the bald areas.
The drugs minoxidil and finasteride may stimulate hair growth in some people. Minoxidil (trade name Rogaine) is a scalp ointment that may maintain hair growth when applied regularly. Finasteride (trade name Propecia) is a pill that may stop hair loss or promote new growth of hair for some men. Because it can cause birth defects, finasteride is not approved for women.
