Despite the popularity of such other drugs as growth hormone, insulin, and thyroid medications, anabolic steroids are still the most popular bodybuilding drugs. Everyone from professional and amateur athletes to bouncers and firefighters uses these androgenic/anabolic drugs to increase muscular size and strength. The trade off, however, is the risk of developing any number of adverse side effects that can endanger health.

Since these drugs affect multiple body systems, for convenience we are going to group the various side effects into categories.

Liver Function

Unlike injectable steroids, orally administered steroids need to be chemically modified to survive the harsh environment of the digestive system and the liver's detoxifying properties. This modification is usually at the steroid's 17th carbon position and is called C-17 methlyization. Although this chemical tinkering enables more of the drug to enter general circulation, it also places the liver at risk. The most frequently reported problems are enzyme abnormalities. While such effects usually disappear after the anabolic steroids are stopped, nevertheless they are indicative of liver damage. And as the liver is the body's primary detoxifying organ, such damage could lead to other more serious problems. This is why athletes who use oral steroids should limit their cycles to 6 to 8 weeks and if at all possible, have their liver enzymes regularly monitored. Injectable steroids don't have such chemical modifications and don't cause the same degree of liver stress.

The Male Reproductive System

Being derivatives of testosterone, it's not surprising that steroids have side effects related to the male hormone. Most of the body's hormones operate on a biofeedback loop. When levels are high, the body shuts down production. When levels are low, the manufacturing machinery is activated. As the body thinks steroids are testosterone, it shuts production of the hormone down which often leads to shrinkage of the testes. This in turn may lead to such other problems as impotence, infertility, and reduced sex drive. It may take the testes months to regain their pre-steroid form after usage.

One of the most unsightly cosmetic side effects of steroid usage is called gynecomastia. Gynecomastia, also known as "bitch tits" is caused by increased levels of circulating estrogens, which ironically are one of the breakdown products of anabolic steroids. As the male breast region also contains estrogen receptors the increased levels of circulation estrogens in males stimulate breast growth. In general, gynecomastia is irreversible.

The Female Reproductive System

In the normal female body small amounts of testosterone is produced and tolerated, but when females take steroids, they may result in irregularities of the menstrual cycle. Other side effects of anabolic steroid use in females are increased sexual desire, enlarging of the clitoris, male pattern boldness, lowering of the voice, and increased facial hair growth. The lowering of the voice, clitoris hypertrophy, and hair loss, are generally irreversible.

The Cardiovascular System

The two main cardiovascular side effects produced by steroids are the elevating of blood pressure and the decreasing of circulating levels of high-density lipoproteins (HDL), the "good" form of cholesterol. Such changes are not life threatening in the short term. But bodybuilders who stay on steroids for years are putting themselves at great risk for developing heart attacks and stroke later in life.

Psychological Effects

Besides their physical effects, steroids may cause increased aggressiveness. Users often welcome this as it helps them train harder and perform better in the competitive field. But such healthy venting of increased aggression may be replaced by incidents of violence outside the gym. Those individuals with short tempers would be wise to avoid steroids.

Besides aggressiveness, anabolic steroid users may become dependent on the drug, with symptoms of withdrawal after cessation of drug use. The withdrawal symptoms may include depression, suicidal behavior, mood changes, and in some cases acute psychosis. Again those with a history of such psychological problems in their family might want to avoid using anabolic steroids all together.