Why does PCOS lead to excess hair growth?

Hirsutism — abnormal hair growth with a male pattern of distribution — is one of the main manifestations of PCOS, with about 70-80% of women with PCOS experiencing this condition.^[1] The primary cause of hirsutism in PCOS is an excess of androgens and an increased sensitivity of hair follicles to androgens, leading to abnormal patterns of hair growth. Reducing androgen secretion is the main treatment for hirsutism, which can be accomplished by using a combined oral contraceptive and antiandrogen treatment regimen or a combination of antiandrogens and another method of contraception (the latter due to the risk of birth defects from antiandrogens). Metformin and lifestyle changes may also be effective.^[1]