Can Poppy Seeds Make You Fail a Drug Test?

The poppy seed defence has been a joke on television for thirty years, which is unfortunate, because for urine testing it is not a joke at all. It is real, it is documented, and it has cost people their jobs.

What almost nobody explains is that the answer is completely different depending on which test you took.

Why food can do this at all

Poppy seeds come from Papaver somniferum — the opium poppy. The seeds themselves contain no meaningful opiate, but they pick up traces of morphine and codeine from the milky latex of the pod during harvesting. Washing and processing reduce it. Nothing removes it entirely.

So a poppy seed bagel is, in a very small way, a dose of morphine. Not a pharmacologically meaningful one — you will feel nothing — but a laboratory does not need you to feel anything.

In urine: yes, and by a wide margin

Two controlled studies make the scale of this clear.

In a 2024 study published in the Journal of Analytical Toxicology, ten participants ate one of five poppy seed food products every day for ten days. Three of the products never produced a positive opiate result. The other two produced positives in every single sample — all 60 were codeine-positive at the 300 ng/mL cutoff, and 45% were also morphine-positive. One participant reached a peak codeine concentration of 13,161 ng/mL.

Reisfield GM et al. (2024) — Urine and hair drug test results associated with daily consumption of codeine-predominant poppy seed food products

An earlier study reached the same conclusion from the other direction. Ten subjects ate 150 g of poppy seed over three weeks, and their urine morphine concentrations ran from 2,929 to 13,827 ng/mL.

Hill V, Cairns T, Cheng C-C, Schaffer M (2005) — Multiple aspects of hair analysis for opiates

For context, a common workplace cutoff for opiates in urine is 300 ng/mL, and a stricter one is 2,000 ng/mL. Those figures clear both. This is not a technicality — it is a person who has taken no drug, returning a result that looks like someone who has.

In hair: no

Here is the part that matters, and it is the reason both studies bothered to collect hair as well.

In the 2024 study, the participants whose urine was positive every single day for ten days had their hair tested on day 20. Only two of the ten had any quantifiable codeine at all, at 41 and 51 pg/mg. The reporting threshold for codeine and morphine is 200 pg/mg. Neither came close. Nobody in the study would have been reported as positive on hair.

The 2005 study found the same. Despite urine morphine in the thousands of nanograms per millilitre, hair collected in the fifth week held 0.05–0.48 ng per 10 mg of hair — that is roughly 5 to 48 pg/mg, averaging about 17 pg/mg. Against a 200 pg/mg threshold, that is background noise.

Why the two tests disagree

It looks like a contradiction. It is not — the two tests are measuring different things.

Urine measures what your body is clearing right now. Eat a poppy seed roll and within hours your kidneys are excreting the traces of morphine and codeine that came with it, concentrated into a small volume of urine. The test catches that flush. It says nothing about whether it happened once or every day for a year.

Hair measures what was in your bloodstream while the hair was growing. A substance is laid into the hair shaft as it forms, in proportion to how much was circulating and for how long. Trace dietary exposure, repeated daily, still amounts to almost nothing in the bloodstream at any given moment — so almost nothing is deposited. Genuine opiate use is orders of magnitude higher, and it shows.

Put simply: urine is sensitive to a single recent event. Hair is sensitive to a sustained pattern. Poppy seeds are a series of tiny events that never add up to a pattern. That difference in what the two samples measure is set out in full in hair testing versus urine testing.

What to do if this has happened to you

If you have returned a positive opiate urine screen and you believe food is the explanation, the practical answer is a hair test covering the same period. It is the standard way to check a disputed opiate result precisely because dietary poppy seed does not register in hair — so a real opiate history and a poppy seed lunch look nothing alike.

Two things strengthen that considerably:

Segmented analysis. Rather than reading the whole 3 cm as one figure, the sample is cut into monthly sections. That shows the pattern over time, not just an average, which is far more informative where a single occasion is in dispute.

Distinguishing which opiate. Poppy seed exposure is characteristically codeine-predominant, with morphine lower. Heroin use produces a metabolite, 6-monoacetylmorphine, that food cannot account for at all. The profile of what was found is often more telling than the fact that something was found.

Neither of those is on the face of a certificate. If the result is contested in a workplace or court matter, have it read by an independent forensic toxicologist and put in writing.

In short

• Poppy seeds genuinely cause positive urine opiate results, at levels well above common cutoffs.
• They do not cause positive hair results — published studies put them at a fraction of the reporting threshold.
• A hair test is therefore the usual way to check a disputed urine opiate positive.
• Declare any poppy seed food on your paperwork before testing, not after the result.

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