Excerpted from a Women’s Health story by Korin Miller

Even if you’ve never touched an illicit drug, it’s easy for the paranoid part of your brain to worry that somehow, some way, something is going to show up on a drug test. Unfortunately, that’s what happened to a new mom in Maryland.

New mom Elizabeth Eden told WBAL-TV that back in April, she was in labor with her daughter at St. Joseph Medical Center when her doctor came in and told her that she tested positive for opiates. Elizabeth told WBAL-TV that she’d heard at some point that eating poppy seeds could give you a false positive, so she flagged that for her doctor.

“I said, ‘Well, can you test me again? And I ate a poppy seed bagel this morning for breakfast,’ and she said, ‘No, you’ve been reported to the state,'” Elizabeth said.

Because of Elizabeth’s positive drug test, her newborn had to stay in the hospital for five days and her mom was assigned to a state case worker for a home check-up. “It was traumatizing,” Elizabeth said of the experience.

She ended up writing a detailed letter to the hospital, spelling out research she’d done on poppy seeds and asking the hospital to raise its threshold for a positive test, or at least warn pregnant women.

Wait, can you really test positive on a drug test from poppy seeds?
Apparently so. Poppy seeds come from the opium poppy plant and contain a trace amount of opioids, the U.S. Anti-Doping Agency (USADA) says.

Though poppy seeds don’t actually contain morphine (opium is about 12 percent morphine), the seeds can become coated by or absorb opium extract when they’re harvested, according to the USADA. “It’s not a high enough concentration for anyone to feel the effects, but it is often high enough to be detected in a urinalysis,” says Jennifer Wider, M.D.

According to the USADA, morphine can sometimes be detected in your pee up to 48 hours after you have poppy seeds. Since everyone’s metabolism is different, it’s hard to say exactly how many poppy seeds will kick you over the threshold, the USADA says.

However, there are a few other factors that determine whether your poppy seed muffin will come back to haunt you—like how well the poppy seeds were washed after they were harvested and how much you actually ate, says Jamie Alan, Ph.D., an assistant professor of pharmacology and toxicology at Michigan State University.

It also depends on the actual test that’s being used, Alan says. Each test has a threshold and those for drug screening in the workplace tend to have a slightly higher threshold to allow for these kinds of things, she says. But ultimately it depends on the guidelines that a particular organization has set.

For the World Anti-Doping Agency (WADA), that threshold is 1.3 micrograms per milliliter. The morphine threshold at the hospital where Elizabeth gave birth is 300 nanograms per milliliter (a much lower threshold), Judith Rossiter-Pratt, chief of the department of obstetrics and gynecology at St. Joseph Medical Center, told WBAL-TV.

According to Rossiter-Pratt, that measurement is typically catches as many drug mis-users as possible. “What you can see on this graph is that if you set the bar here, you would only identify true positives, but you would also miss quite a few individuals who did use drugs and were considered screened negative,” she told WBAL-TV about the hospital’s policy.

If you know you have a drug test coming up, you really should avoid all products with poppy seeds for at least a few days before the test, Wider says. That includes poppy seed dressings, muffins, and bagels, which are usually heavily coated in them.

As for Elizabeth, once her situation was realized as a legitimate case of the poppy seed defense, her file was closed, per WBAL-TV.