Is androstenedione legal?

Following the federal regulation of steroids, athletes and scientists were looking for the next big thing in athletic supplements. That came with the invention of pro-hormones. Androstenedione, the pro-hormone made popular by Mark McGwire, is a precursor to testosterone and oestrogen.

The legality of this substance was forever changed after Congress passed the Anabolic Steroid Control Act in 2005. Androstenedione is illegal to distribute, possess or use. The sale of androstenedinoe was banned in 2004 by the FDA.


The history of pro-hormones begins where the legality of steroids ends. As steroids became federally controlled substances, individuals began anew to search for their replacement. If the production, sale and administration of synthetic testosterone was illegal under federal law, interested parties skirted the intent of the law and took the next logical step to developing products that contained not testosterone, but the precursors of testosterone--substances that the body could readily convert into bioavailable testosterone. The first of these substances to achieve widespread popularity in the United States was androstenedione. Androstenedione, along with numerous other pro-hormones, was made illegal by the 2005 amendments to the Anabolic Steroid Control Act.


Androstenedione is a naturally occurring substance in the body. It is made by the adrenal glands and the gonads in both men and women and is the precursor to both testosterone and oestrogen. As a supplement, androstenedione was shown to increase testosterone levels across an eight-hour period upon taking a dose of 300mg a day. Estradiol levels increased as well. Studies conducted at a daily dose of 50mg, 100mg and 300mg all showed no significant effect on body fat, muscle size or strength.

Side Effects

Although no notable effect was seen on muscle size or strength, andro users did experience oestrogenic side-effect, including increased risk of prostate cancer, heart disease, prostate enlargement, lowered libido (in men) and the possibility of developing gynaecomastia. On balance, with zero real benefits and a host of undesirable side-effects, androstenedione was a swing and a miss.


However, androstenedione did give birth to the pro-hormone industry, and did lead to the development of several other related substances that were successful. Those substances come close to the efficacy of anabolic steroids while minimising the potential for side-effects. Two of these pro-hormone success stories were 4-androstenediol (4-ad) and 19-nor-4-androstenediol, both of which had roughly 80 per cent of the effectiveness of anabolic steroids and fewer side-effects than the failed androstenedione.


The irony of the federal government's stance against the use of anabolic steroids is that in passing the original Anabolic Steroid Control Act and outlawing these substances, they created the impetus for the development of pro-hormones--substances that were not as effective but were as dangerous than steroids. Not only do pro-hormones have decreased efficiency coupled with undesirable side-effects, but the medical community has next to no established body of research on the long-term effects of these newly developed compounds (unlike steroids, which have existed since the 1930s). It is difficult to predict whether the next series of legal sports supplements will produce near the number of hazards caused by the pro-hormone craze, but it is a certainty that, with the declaration of pro-hormones such as androstenedione as banned substances, we will soon find out.