Those who make and distribute the steroid-like supplement made famous by baseball's Mark McGwire are about to hear from the government.
Health and Human Services Secretary Tommy Thompson told a news conference that letters are going out to 23 manufacturers of androstenedione, known popularly as "andro," telling them to cease their production.
Andro is a steroid precursor, which means the body uses it to make testosterone. The Food and Drug Administration says that means it poses the same health risks as directly using an anabolic steroid.
Thompson says firms refusing to stop distributing andro and other dangerous supplements may face seizure of the products, injunctions or prosecution.