5 Ways Teens Might Cheat on Drug Tests—and How to Catch Them

4. Popping vitamins. Perhaps it's because niacin (aka vitamin B3) is known to aid metabolism, or perhaps it's because Scientologists are said to take it in excess to flush their bodies of toxins. Whatever the reasons, some teens got the idea that extreme doses of this vitamin would erase any trace of their illicit drug use. Instead, it almost cost them their lives. In two separate incidents, emergency physician Manoj Mittal of Children's Hospital of Philadelphia has found adolescents who downed at least 150 times the daily recommended dose of niacin (15 mg) to cheat drug tests. (He described the cases last year in the Annals of Emergency Medicine.) Both kids were vomiting, had low blood sugar, and had "significant" liver toxicity when they arrived at the ER. And the niacin didn't even do what they'd intended; both tested positive for illicit drugs. "People might think that since [niacin] is a vitamin it's harmless," says Mittal. "But these cases suggest that our bodies have limits."

5. Swapping urine samples. Whether they use a friend's clean urine, synthetic pee, or even freeze-dried urine purchased online, some teens try to pass off foreign samples as their own, says Levy. The biggest tip-off is temperature. "Anything significantly lower than body temperature is suspicious," says Dasgupta, which is why some have tried to shuttle samples in armpits or taped to thighs to keep them warm. Possibly the oddest trick of all is a device marketed to those trying to beat witnessed drug collections, says Wu: a sort of prosthetic penis called the "Whizzinator" that claims to come equipped with clean urine "guaranteed" to remain at body temperature for hours, with the help of special heat pads. "Believe it or not, [the prosthesis] comes in different colors," says Wu.