Testosterone is a male hormone that has anabolic and androgenic effects. The anabolic effect includes promoting bone density, the growth of muscle, and the rapid recovery from injury. The androgenic or masculinising effect is responsible for developing and maintaining all male characteristics. These include the penis, testicles, muscle mass, deep voice and facial hair.
Even though testosterone is called a male sex hormone, it occurs naturally in women as well, but in much smaller amounts. There are many legitimate medical uses for steroids, such as treating osteoporosis. However, men and women users who take steroids illegally do so to increase lean muscle mass.
The abuse of steroids is most common among professional athletes and bodybuilders. Teenagers and adults who feel they need to look muscular to feel good about themselves may also abuse steroids.