Anabolic steroids (the proper scientific term being ‘anabolic-androgenic steroids’, abbreviated AAS) are synthetic testosterones prescribed to treat a medical condition where hormonal deficiencies are present, or used illegally with the desire of increasing muscle mass and/or the appearance of masculine sex characteristics. Use is most common among young men. Anabolic steroids can be taken orally, injected into the muscles, or rubbed on the skin in the form of a cream. There are many effects of the unregulated use of anabolic steroids by young men, including testicle shrinkage, reduced sperm count or infertility, baldness, development of breasts (gynecomastia), and an increased risk for prostate cancer.