Cyproterone acetate also interferes with DHT binding at hormone receptor sites on hair follicle cells. When used to treat androgenetic hair loss in women, it is combined with a powerful estrogen hormone called ethinyl estradiol. Estrogens are a class of hormones that are prescription anti-androgens. Estrogens counterbalance and help regulate androgens. Estrogens compete with androgens at hormone receptor sites on hair follicle cells, but do not trigger hair loss.
Women generally have higher proportions of estrogens than androgens when compared to men.
The high levels of estrogen hormones in women usually protects those women who have a genetic predisposition for androgenetic hair loss from losing their hair. When women with a genetic predisposition to androgenetic hair loss produce reduced amounts of estrogens, or increased levels of androgens, they may experience pattern hair loss. Estrogen treatments for hair loss attempt to elevate estrogen levels in the body. Estrogen treatment may cause irregular menstrual cycles, and possibly increased risk of cancer in women. Men may experience decreased sex drive.