The American College of Sports Medicine acknowledges that AAS, in the presence of adequate diet, can contribute to increases in body weight, often as lean mass increases and that the gains in muscular strength achieved through high-intensity exercise and proper diet can be additionally increased by the use of AAS in some individuals.These effects include harmful changes in cholesterol levels (increased low-density lipoprotein and decreased high-density lipoprotein), acne, high blood pressure, liver damage (mainly with most oral AAS), and dangerous changes in the structure of the left ventricle of the heart.AAS use in adolescence is also correlated with poorer attitudes related to health. Development of breast tissue in males, a condition called gynecomastia (which is usually caused by high levels of circulating estradiol), may arise because of increased conversion of testosterone to estradiol by the enzyme aromatase.Another male-specific side-effect that can occur is testicular atrophy, caused by the suppression of natural testosterone levels, which inhibits production of sperm (most of the mass of the testes is developing sperm).
There is also the risk that an intimate partner or child may come in contact with the application site and inadvertently dose himself or herself; children and women are highly sensitive to testosterone and can suffer unintended masculinization and health effects, even from small doses.
Injectable steroids are typically administered into the muscle, not into the vein, to avoid sudden changes in the amount of the drug in the bloodstream.
In addition, because estered testosterone is dissolved in oil, intravenous injection has the potential to cause a dangerous embolism (clot) in the bloodstream.
Studies indicate that the anabolic properties of AAS are relatively similar despite the differences in pharmacokinetic principles such as first-pass metabolism.
However, the orally available forms of AAS may cause liver damage in high doses.