While the steroids do deliver on the promise of muscle mass, they also come with side effects. The testicles may shrink and fertility may be affected; the user may become super-aggressive and anger easily, a consequence sometimes referred to as “’roid rage;” prominent breasts may develop in men; impotence may occur; prostate glands may enlarge; and hair may fall out, resulting in baldness. In women, the steroid may make her take on more male qualities, including increased body hair, a deeper voice, an enlarged clitoris, hair loss and infrequent periods.

In both men and women, steroids may cause severe cases of acne, liver problems, an increased possibility of ruptured tendons or tendonitis; increased levels of low-density lipoprotein (bad cholesterol) and decreased levels of high-density lipoprotein (the good cholesterol); high blood pressure; heart problems; psychiatric disorders, including depression; insomnia; infections like hepatitis or HIV if injecting the drugs; and inhibited growth and development.

Because long-term studies of these drugs have not yet been completed, the problems they create are still largely a matter of observation. The other factor to consider is that most professional sports organizations have banned taking performance-enhancing drugs, and law enforcement is increasingly cracking down on their distribution and manufacture. That is a double-edged sword -- what’s increasingly available via black markets may be impure or sub-standard.

Androstenedione

Anyone who follows professional baseball will remember how St. Louis Cardinals slugger Mark McGwire kept a container of this powdered hormone in his locker. Although the use wasn’t banned, it raised issues about McGwire’s home-run prowess, resulting in his shunning by the establishment and a subsequent ban of androstenedione by baseball.