In the U.S., where consumers spent nearly $24 billion on dietary supplements in 2007, the Food and Drug Administration is warning against dozens of “natural” weight-loss products found to contain undeclared and potentially dangerous drugs, the New York Times reports. Of the 69 tainted supplements, the best-known—a weight-loss capsule called StarCaps—was discovered to contain bumetanide, a potent diuretic that can have potentially serious side effects. It has since been pulled from store shelves. Hidden drugs can cause elevated blood pressure, seizures, or toxic interactions with other medication, doctors warn, noting they can also make it difficult to diagnose patients. Grady Jackson, a defensive tackle with the Atlanta Falcons who said he used StarCaps, failed a drug test after testing positive for bumetanide, which is banned by the National Football League. He’s now filed a class-action lawsuit against the owner of StarCaps and stores where he purchased it. The FDA, which is continuing its investigation, has posted a full list of the tainted pills on its website.