alt Hacker NewsMelatonin pills seem to have extremely bad quality control:
"Melatonin content varied from an egregious −83% to +478% of labeled melatonin and 70% had melatonin concentration ≤ 10% of what was claimed. Worse yet, the content of melatonin between lots of the same product varied by as much as 465%.
[...]
The last disturbing finding was more than a quarter of melatonin products contained serotonin, some at potentially significant doses."
https://pmc.ncbi.nlm.nih.gov/articles/PMC5263069/
"In products that contained melatonin, the actual quantity of melatonin ranged from 74% to 347% of the labeled quantity. Twenty-two of 25 products (88%) were inaccurately labeled, and only 3 products (12%) contained a quantity of melatonin that was within ±10% of the declared quantity. [...] Serotonin was not detected in any product."
https://jamanetwork.com/journals/jama/fullarticle/2804077
"Half of the products tested met the label’s claim for melatonin, which means they fell between 76 and 126 percent of the claimed amount. Of the products tested, 20 had between 0 and 76 percent of the labeled content, and 35 had between 126 and 667 percent."
https://www.washingtonpost.com/wellness/2025/06/25/melatonin...
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One more relevant study, but on the health effects of long term melatonin use:
https://newsroom.heart.org/news/long-term-use-of-melatonin-s...
"The main analysis found:
* Among adults with insomnia, those whose electronic health records indicated long-term melatonin use (12 months or more) had about a 90% higher chance of incident heart failure over 5 years compared with matched non-users (4.6% vs. 2.7%, respectively). * There was a similar result (82% higher) when researchers analyzed people who had at least 2 melatonin prescriptions filled at least 90 days apart. (Melatonin is only available by prescription in the United Kingdom.)
A secondary analysis found:
* Participants taking melatonin were nearly 3.5 times as likely to be hospitalized for heart failure when compared to those not taking melatonin (19.0% vs. 6.6%, respectively). * Participants in the melatonin group were nearly twice as likely to die from any cause than those in the non-melatonin group (7.8% vs. 4.3%, respectively) over the 5-year period."
However they were not able to control for severity of the insomnia and used dosage, because that data weren't in the dataset.
I really wish they'd name-and-shame the brands. I don't see how hiding it helps encourage better behavior. If anything, it seems like they should be publishing legal ranges, and rewarding testing labs that catch things outside it by fining failures.
> Melatonin pills seem to have extremely bad quality control:
Melatonin is treated as a dietary supplement in the US rather than a drug, and this seems to be a widespread problem with supplements, given the incredibly lax regulatory regime.