This medication is used in men who do not make enough of a natural substance called testosterone. Testosterone belongs to a class of drugs known as androgens. Testosterone helps the body to develop and maintain male sexual characteristics (masculinity), such as a deep voice and body hair. It also helps to maintain muscle and prevent bone loss and is necessary for natural sexual ability/desire. Testosterone may also be used in certain adolescent boys to cause puberty in those with delayed puberty. This product should not be used by women.