The telltale tingle and aroma of muscle-ache creams are familiar to any athlete who pushes herself too hard once in a while. But the death of 17-year-old Arielle Newman from Staten Island, New York, made us wonder: Are they safe? Newman died from an overdose of methyl salicylate, an ingredient in the sports creams and adhesive pads she'd been using on her legs. "Overdoses from topical medications are extremely rare. In fact, this is the first documented case I'm aware of," says Robert Sallis, M.D., president of the American College of Sports Medicine. "Perhaps something unique to Newman's skin caused a much larger amount of methyl salicylate to enter her bloodstream." When used as directed, the chemical causes a warming sensation and helps dull muscle aches; but if used in high doses or for weeks at a time, it can build up in the bloodstream, causing dizziness, shallow or rapid breathing, and nausea. (Ringing in your ears is usually the first sign of an overdose.) If you're rubbing on the creams for occasional aches, don't worry-just follow the dosage instructions. If the soreness doesn't subside, see your doctor.