Steroids, the popular name for synthetic (man-made) substances related to the male sex hormones, promote muscle growth and the development of male sexual characteristics. Steroids are legally available only with a prescription. They are prescribed to treat conditions such as delayed puberty, some types of impotence, and body-wasting in patients suffering from AIDS (acquired immunodeficiency syndrome). Steroids are abused, often by athletes, to enhance athletic performance and to improve physical appearance. Source: National Drug Intelligence Center, U.S. Department of Justice.