Androgens provide the sex-drive, sometimes called libido, which makes men want sex. Androgens arouse sexual feelings, sometimes causing erections to happen at odd times during the day. Another action of androgens is to give a man 'secondary sex characteristics' such as body hair, deepened voice, muscle bulk and other male characteristics.

The male sex hormones, or androgens, are Testosterone, Dihydrotestosterone, Androstenedione, and Dihydroepiandrosterone (DHEA). They are made in the Testes (testicles) and Adrenal Glands (situated in the kidneys). These are triggered by Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH) which are made by the Pituitary Gland in the brain. The Pituitary Gland in turn responds to triggers from higher centres by producing more FSH and LH. If androgen levels are low, the Pituitary Gland produces more of these stimulating hormones keeping androgen levels in the blood at a steady rate - a sort of self regulating feedback loop mechanism.

With the body keeping levels steady in this way, it is very uncommon for imbalance to happen. For this reason, testing of hormone levels is done before giving extra hormones. Taking hormones you do not need will prevent the body making them naturally, and can be harmful.