The Food and Drug Administration has issued a warning about a particular brand of vitamin B supplements which contain steroids but doesn’t say so on the label.

Healthy Life Chemistry By Purity First B-50 vitamins have received several complains by both men and women who reported adverse reactions, such as unusual hair growth, missed menstrual cycles, impotence and low testosterone. Lab tests also found abnormal liver and thyroid function and elevated cholesterol levels.

A spokesperson for the FDA says that legal action may be pending on behalf of the consumers who ingested the vitamins since the labels contain no mention of steroids; testing revealed that the supplement contained two different types, methasterone and dimethazine.

“Products marketed as a vitamin but which contain undisclosed steroids pose a real danger to consumers and are illegal,” Howard Sklamberg said.

Despite the potential legal implications, the manufacturer–Mira Health Products, LTD.–refuses to issue a voluntary recall of the products. Now, the NFL has alerted all players to discontinue use of the vitamin, as it may contribute to a failed drug test. The NFLPA issued a statement to players, warning them that a positive test following use of the supplement will result in suspension.

“Any player who has taken the product and thereafter tests positive will be suspended four games, regardless of the reality that the supplement was spiked with banned substances. Several years ago, multiple players were suspended for taking StarCaps, a weight-loss supplement that secretly contained a prescription diuretic. Players are responsible for the contents of their body chemistry, and the league and the NFLPA have created a list of approved supplements. If a player strays from the list, the player risks a positive test.”