Although the original pharmaceutical steroid Dianabol did have some adverse or annoying side effects such as possible damage to the liver, Legal Dianabol does not cause such adverse effects. For instance, the pharmaceutical steroid could also cause gynecomastia, which is a sudden decrease in the male hormone, testosterone, and a resulting increase of estrogen, the female hormone, in the body. This can result in enlarged breast tissue in some men and often causes pronounced water retention, which can be a hindrance to engaging in long periods of strenuous physical activity.
After the Kefauver Harris Amendment was passed in 1962, the . FDA began the DESI review process to ensure the safety and efficacy of drugs approved under the more lenient pre-1962 standards, including Dianabol.  In 1965, the FDA pressured CIBA to further document its legitimate medical uses, and re-approved the drug for treating post-menopausal osteoporosis and pituitary-deficient dwarfism .  After CIBA's patent exclusivity period lapsed, other manufacturers began to market generic metandienone in the .