Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin…
Since supplement melatonin has been measured at anywhere from a fifth to nearly five times the label dose, is there a brand you'd trust, or a tested product I should ask for instead?
Reasonable evidence with real limitations. how we score evidence
Caveat on this rating: Thirty-one samples of Canadian products bought in 2016; it does not measure how common the problem is across the whole market, and the later US gummy analysis (Cohen 2023, below) did not detect serotonin in any product it tested, so the serotonin contamination finding has not been replicated in the US supply.
In the United States melatonin is sold over the counter as a dietary supplement under the Dietary Supplement Health and Education Act of 1994 (DSHEA). The FDA does not review it for safety or effectiveness before sale, does not verify that a tablet or gummy contains the dose printed on the label, and has never approved melatonin to treat insomnia or any other condition. That regulatory posture is unusual internationally: melatonin is a hormone, and in the United Kingdom and the European Union it is a prescription-only medicine, not a supplement — prolonged-release melatonin (Circadin, 2 mg) has been authorised by the European Medicines Agency since 2007 for short-term treatment of insomnia in adults aged 55 and over, and a paediatric prolonged-release formulation (Slenyto) was authorised in 2018 for insomnia in children and adolescents with autism spectrum disorder or Smith-Magenis syndrome. A British traveller cannot buy at a pharmacy what an American buys at a supermarket checkout, and the American product's actual content is not verified by anyone.
Chemical analysis of 31 commercial melatonin supplement samples found actual melatonin content ranging from 83% below to 478% above the labelled amount, with lot-to-lot variation within a single product of as much as 465%; more than 71% of products missed their own label by more than a 10% margin, and the variability was unrelated to manufacturer or product type. Serotonin — a controlled substance in this context — was detected in 8 of the supplements at 1 to 75 micrograms. Someone taking "the same" melatonin nightly may be taking a fifth of the stated dose one month and five times it the next.
Worth asking
Since supplement melatonin has been measured at anywhere from a fifth to nearly five times the label dose, is there a brand you'd trust, or a tested product I should ask for instead?
Source
Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content. — Erland LA, Saxena PK. (2017)
Reputable peer-reviewed journal
Read the source: https://doi.org/10.5664/jcsm.6462
DOI: 10.5664/jcsm.6462
How this was scored
- Study design
- Cross-sectional study / survey
- Funding
- Independently funded
- Published in
- Reputable peer-reviewed journal
- Sample size
- 31
- Preregistered
- No
- Conflicts disclosed
- Yes
- Independent of proponent
- Yes
- Retracted
- No
Read the full scoring rubric, including what it can't tell you.
Published August 19, 2026.
Where we put this study in context
Questions
How strong is the evidence behind this?
Resolv rates this source "moderate evidence". Reasonable evidence with real limitations. It scores 60 out of 100 on our published rubric. One caveat travels with that badge: Thirty-one samples of Canadian products bought in 2016; it does not measure how common the problem is across the whole market, and the later US gummy analysis (Cohen 2023, below) did not detect serotonin in any product it tested, so the serotonin contamination finding has not been replicated in the US supply. The score is calculated from recorded facts about the source — study design, funding, publication venue, sample size, preregistration — not typed in by an editor.
What is the source for this?
Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content. — Erland LA, Saxena PK. (2017). Published in: Reputable peer-reviewed journal. DOI: 10.5664/jcsm.6462. The full source is linked on this page so you can read it yourself.
Who paid for this research, and does that matter?
Study design: Cross-sectional study / survey. Funding: Independently funded. The researchers were independent of whoever benefits from the result. Industry sponsorship is one of the most reliably measured biases in medicine, which is why funding carries real weight in the score rather than sitting in a footnote.
Is melatonin, circadin, slenyto, n-acetyl-5-methoxytryptamine, melatonin gummies FDA approved for this use?
No. Its current status is: Not FDA-evaluated for this use. In the United States melatonin is sold over the counter as a dietary supplement under the Dietary Supplement Health and Education Act of 1994 (DSHEA). The FDA does not review it for safety or effectiveness before sale, does not verify that a tablet or gummy contains the dose printed on the label, and has never approved melatonin to treat insomnia or any other condition. That regulatory posture is unusual internationally: melatonin is a hormone, and in the United Kingdom and the European Union it is a prescription-only medicine, not a supplement — prolonged-release melatonin (Circadin, 2 mg) has been authorised by the European Medicines Agency since 2007 for short-term treatment of insomnia in adults aged 55 and over, and a paediatric prolonged-release formulation (Slenyto) was authorised in 2018 for insomnia in children and adolescents with autism spectrum disorder or Smith-Magenis syndrome. A British traveller cannot buy at a pharmacy what an American buys at a supermarket checkout, and the American product's actual content is not verified by anyone.
Is this medical advice?
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.