Some Melatonin Supplements Have Dramatically Different Dosages Than Advertised, New Study Says

People who take the over-the-counter supplement melatonin for better sleep may be getting more—or less—of the drug than they think, according to a new study published Apr. 24 in JAMA. In an analysis of 25 different gummy supplements claiming to contain melatonin, researchers at the Cambridge Health Alliance and the University of Mississippi found that 22 of them contained dramatically different amounts than were stated on the bottle.

The 22 mislabeled products were found to have melatonin quantities ranging from 74% to 247% of the amounts listed on their labels. One contained no melatonin at all. Lead author Dr. Pieter Cohen, an associate professor at Harvard Medical School and internist at Cambridge Health Alliance, says that this didn’t surprise him. Even though melatonin supplements have long been “thought to be relatively safe,” the U.S. Food and Drug Administration (FDA) does not regulate supplements as strictly as they do over-the-counter drugs. “Supplement manufacturers don’t need to keep the FDA happy,” he says. When it comes to quantities, “they don’t need to prove anything to the agency—so they do whatever they want to. Not obsessing about quality control keeps things a lot less expensive to make.”
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Cohen decided to take a closer look at melatonin gummies after a 2022 report found that calls to U.S. poison-control centers for pediatric melatonin consumption jumped more than 500% from 2012 to 2021. “​​The majority of those calls were due to unintentional ingestions,” he says, and gummies are especially appealing to kids, who can mistake the medication for candy. Though most of the kids were okay, nearly 20% of the poison-control calls reported some symptoms, which included gastrointestinal distress, cardiovascular symptoms, and more. Melatonin has not been well-studied in children, even though about 10% of U.S. parents have at least one child who takes it, according to Consumer Reports.

Read More: What the Science Says About the Health Benefits of Vitamins and Supplements

Past research has also found that melatonin supplements vary wildly in how much of the drug they contain. A Canadian study in 2017 found that 71% of over-the-counter supplements tested—some of which were also likely sold in the U.S. at the time—had mislabeled melatonin doses by a margin of at least 10%, the same threshold used in the new paper. That these findings have essentially been replicated more than five years later with a newer generation of products shows how the under-regulated supplement market in the U.S. provides no real incentive for manufacturers to change, Cohen says.

Since melatonin is a hormone made in the brain, released to make us feel tired when it gets dark outside, companies will often highlight in their marketing that the top-off provided by a melatonin supplement is “natural.” But many of their actual doses far exceed what the body makes on its own, says Cohen. “What we know is that if you give a 20-year-old adult a very small amount of melatonin in the morning—like a 10th of a milligram, or three 10ths of a milligram—it raises their levels up to the normal nighttime levels,” says Cohen. Popular over-the-counter supplements often claim to contain as much as five or even 10 milligrams per dose. Considering the unpredictable dosages found in Cohen’s study, a nighttime melatonin routine could add many times what the body is able to produce.

If melatonin has worked for you in the past or you want to give it a try, there are ways to guard against too large of a dose, says Cohen. Look out for supplements with a high-quality third-party verification stamp, which come from organizations such as the U.S. Pharmacopia (USP) or NSF International, which test and approve certain manufacturers of supplements.

But before you try melatonin, consider cleaning up your sleep habits first to see if it helps. Taking melatonin isn’t in the same category as “listening to classical music to sleep, or drinking a warm glass of milk,” says Cohen. “Extra classical music isn’t going to harm you. Melatonin is a medication.”