Androgens are a group of steroids that have masculinizing effects in both males and females. Testosterone is the most important androgen, produced primarily in the testes in males and in smaller amounts in ovaries and adrenal glands of both sexes. Androgens are required for normal male maturation, sperm production, muscle growth, and bone strength. They work by binding to nuclear receptors in target cells. Therapeutic uses include treatment of hypogonadism and wasting diseases, while adverse effects include acne, hair growth, and prostate issues. Antiandrogens can counter male hormonal actions and are used to treat prostate cancer.