Anabolic steroids include testosterone and any drugs chemically and pharmacologically related to testosterone that promote muscle growth; there are numerous drugs of this kind. Anabolic steroids are used in clinical practice for hypogonadism to treat men with low testosterone levels. In addition, because anabolic steroids are anti-catabolic and improve protein utilization, they are sometimes prescribed for burn patients, bedridden or debilitated patients to prevent muscle wasting.
Some doctors prescribe anabolic steroids for AIDS-depleted or cancer patients. However, there is little data to recommend such a therapy and little guidance on how additional androgens may affect the development of underlying diseases. Testosterone has a reputation for healing wounds and damaged muscles, although there is little evidence to support these claims.
Anabolic steroids are used illegally to increase muscle mass and strength; training in resistance exercises and a specific diet can amplify these effects. There is no direct evidence that anabolic steroids increase endurance or speed, but substantial circumstantial evidence suggests that athletes who take them may be more likely to do high-intensity training. Muscle hypertrophy is clearly observed.
Estimates of lifetime morbidity from anabolic steroid abuse range from 0.5% to 5% of the population, but the subpopulations differ significantly (for example, higher rates in bodybuilders and professional athletes). In the United States, the reported enrollment rate is between 6 and 11% among high school students, including an unexpected number of non-athletes, and about 2.5% among high school girls.