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This article is from the WebMD News Archive

Drug Tests Often Trigger False Positives

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May 28, 2010 (New Orleans) -- If your child insists his positive drug test results are a mistake, there's a chance he could be telling the truth.

Drug tests generally produce false-positive results in 5% to 10% of cases and false negatives in 10% to 15% of cases, new research shows.

Eating as little as a teaspoon of poppy seeds -- less than the amount on a poppy seed bagel -- can produce false-positive results on tests for opioid abuse, says Dwight Smith, MD, of the VA Medical Center in Black Hills, S.D.

The poppy seeds can lead to false-positive results for two or three days, he says, yet one recent study showed only about 50% of doctors were aware of the problem.

Knowing the tests' limitations is crucial given that about 150 million drug tests were conducted in the United States last year, he says.

"We drug test everyone, our students, our athletes," Smith says.

Also, many private and federal employers require regular testing, he says.

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