Methyltestosterone, sold under the brand names Android, Metandren, and Testred among others, is an androgen and anabolic steroid (AAS) medication which is used in the treatment of low testosterone levels in men, delayed puberty in boys, at low doses as a component of menopausal hormone therapy for menopausal symptoms like hot flashes, osteoporosis, and low sexual desire in women, and to treat breast cancer in women. It is taken by mouth or held in the cheek or under the tongue. Side effects of methyltestosterone include symptoms of masculinization like acne, increased hair growth, voice changes, and increased sexual desire. It can also cause estrogenic effects like fluid retention, breast tenderness, and breast enlargement in men and liver damage. The drug is a synthetic androgen and anabolic steroid and hence is an agonist of the androgen receptor (AR), the biological target of androgens like testosterone and dihydrotestosterone (DHT). It has moderate androgenic effects and moderate anabolic effects, which make it useful for producing masculinization. Methyltestosterone was discovered in 1935 and was introduced for medical use in 1936. It was made shortly after the discovery of testosterone and was one of the first synthetic AAS to be developed. In addition to its medical use, methyltestosterone is used to improve physique and performance, although it is not as commonly used as other AAS for such purposes due to its androgenic effects, estrogenic effects, and risk of liver damage. The drug is a controlled substance in many countries and so non-medical use is generally illicit. Uses Medical Methyltestosterone is or has been used in the treatment of delayed puberty, hypogonadism, cryptorchidism, and erectile dysfunction in males, and in low doses to treat menopausal symptoms (specifically for osteoporosis, hot flashes, and to increase libido and energy), postpartum breast pain and engorgement, and breast cancer in women. It is specifically approved in the United States for the treatment of hypogonadism and delayed puberty in males and the treatment of advanced inoperable breast cancer in females. It was also approved in low doses in combination with esterified estrogens for the treatment of moderate to severe vasomotor symptoms associated with menopause in women in the United States, but this formulation was discontinued and hence is no longer used. Methyltestosterone is less effective in inducing masculinization than testosterone, but is useful for maintaining established masculinization in adults. The dosages of methyltestosterone used are 10 to 50 mg/day in men