(CNN) -- Federal regulators warned consumers to avoid one brand of vitamin B dietary supplement because it contains potentially harmful anabolic steroids.
Preliminary lab tests showed the product, Healthy Life Chemistry By Purity First B-50, contains methasterone, a controlled substance, and dimethazine, the Food and Drug Administration said.
"Products marketed as a vitamin but which contain undisclosed steroids pose a real danger to consumers and are illegal," said Howard Sklamberg, director of the FDA's compliance office.
Regulators received 29 complaints associated with the product, including fatigue, muscle pain and cramps, and liver and thyroid problems, the FDA said.
Women also reported unusual hair growth and missed menstruation, and men reported impotence and low testosterone.
Some patients were hospitalized, the FDA said in a statement, but no deaths were reported.
Anyone who used the product and has symptoms should seek medical care and report the case to the FDA, regulators said.
The product manufactured by Purity First Health Products is sold online and in stores. The company has declined to voluntarily recall the product or to warn consumers about the potential for injury, according to the FDA.