Fluoxymesterone (CAS 76-43-7) is a man-made form of testosterone, a naturally occurring sex hormone that is produced in a man's testicles. Small amounts of testosterone are also produced in a woman's ovaries and adrenal system.
It is used in men and boys to treat conditions caused by a lack of this hormone, such as delayed puberty or other hormonal imbalances.
It is also used in women to treat breast cancer that has spread to other parts of the body. Fluoxymesterone treats only the symptoms of metastatic breast cancer but does not treat the cancer itself.