According to a 2007 survey made by the British HFL Sport Science, US weight loss and athletic supplements were found to have steroids in trace amounts. Twenty-five percent of the 52 samples analyzed were found to have undisclosed presence of anabolic steroids.

Since December last year, more than 70 weight loss supplements were discovered by FDA to contain potentially dangerous ingredients.

In July, the FDA issued a warning against bodybuilding supplements that contain steroid-like ingredients. These supplements were found to contain actual steroids. The agency named specific brand names aside from their general warning. FDA also received reports of men who were diagnosed with serious liver injuries, kidney failure, and encountered heart attacks and pulmonary embolism due to taking these supplements.

According to Travis Tygart, chief executive of US Anti-Doping Agency, people especially athletes should talk to a doctor before taking any supplements. He added that athletes should take these supplements at their own risk.

Consumers should be suspicious of supplements that claim to be “herbal” versions of prescription substances.

Ed Wyszumiala, general manager of NSF International, a non-profit organization that certifies supplement’s safety, believes that steroids and other undisclosed drugs may get into products both deliberately and unintentionally.

From The Wall Street Journal:

Finally, people should watch carefully for any symptoms that start after they take a new supplement. Among the warning signs cited by the FDA in its public-health advisory on products that may contain steroids are nausea, weakness or fatigue, fever, abdominal pain, chest pain, shortness of breath, yellow corneas and skin, and discolored urine. Most of those are signs of liver or heart problems.