Hair loss is surprisingly common in women, affecting more than 30 million in the US, according to the American Academy of Dermatology. It can start as early as puberty or much later in life. In fact, 38 percent of women who are 70 years or older experience hair loss—in part because hair thickness decreases with age, especially after menopause. The condition often leads to low self-esteem, social anxiety, and self-imposed isolation.
Female pattern hair loss (FPHL) is characterized by thinning over the top of the scalp and sometimes the sides. In men, a male hormone known as an androgen is primarily responsible for hair loss, but the main cause of FPHL appears to be less clear-cut.
Women normally produce male hormones too, and in some cases the condition is associated with excessive androgen levels. Other types of hair shedding in women may be related to oestrogen loss or significant changes in oestrogen levels, as in the postpartum period or in menopause. Hair loss can also result from breakage during hair treatments and styling, certain medication—including hormones—and conditions like iron deficiency, severe dieting, thyroid disease, lupus, and even stress.
Finasteride is approved by the Food and Drug Administration to treat male pattern hair loss (also called androgenetic alopecia). At higher doses, it’s also approved to reduce the symptoms of enlarged prostate in men. It works by blocking the enzyme that is responsible for the conversion of testosterone to dihydrotestosterone, the androgen that causes the prostate to enlarge. It also reduces dihydrotestosterone levels in the scalp, which slows hair loss and even increases hair growth.
