Male pattern baldness, also called androgenetic alopecia, is the
most common type of hair loss in men. At some point in their
lives, up to 50 percent of all men will be affected by male
pattern baldness to some extent. Male pattern baldness is both
genetic, and associated with the male sex hormones called
androgens. Androgens have many functions, one of which is to
regulate hair growth. Each strand of your hair grows out of a
little hole in your skin called a follicle. Normally, an
individual strand of hair grows for two to six years, goes
through a resting stage for several months, falls out, and is
replaced by a new hair strand. With male pattern baldness, the
hair follicle becomes smaller. It grows shorter and finer
strands, and eventually stops growing hair altogether. The
common cause of male pattern baldness—heredity—is usually
harmless. However, sometimes it has more serious causes, such as
certain cancers, medications, thyroid conditions, and anabolic
steroids. See your doctor if hair loss occurs afte