Dihydrotestosterone (DHT) is a byproduct of the breakdown of the male hormone testosterone. Dihydrotestosterone is considered the essential androgenic hormone. DHT is responsible for the formation of male primary sex characteristics during embryonic life and responsible for the development of most secondary sex characteristics in males at puberty, and it continues to be important to male sexual function throughout adult life. In older men the level of DHT increases and is responsible for male pattern hair loss and for benign prostate hypertrophy. Inhibition by the drugs Proscar (for prostate) and Propecia (for hair loss) and certain herbal therapies are designed to combat these conditions.