Serotonin, a potent neurotransmitter and strictly controlled substance, is present as an unlabelled contaminant in approximately 26% of commercial melatonin supplements, with detected concentrations ranging from 1 to 75 micrograms per dose. The presence of this biologically active compound in sleep aids raises significant safety concerns, particularly regarding potential adverse interactions with other medications or the risk of serotonin syndrome in sensitive individuals.

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Evidence from Studies

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Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content

Cross-Sectional Study

2017 Feb 15

A laboratory analysis of popular melatonin pills discovered that roughly a quarter of them were contaminated with serotonin, a different brain chemical that could cause unwanted side effects.

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Source Study

Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content

Score: 29

DOI: 10.5664/jcsm.6462

Similar Assertions

Some melatonin pills contain unlisted serotonin, and this isn't just because of added herbs. It's likely caused by factory mix-ups, chemical breakdowns, or poor quality control during manufacturing and packaging.

73%

When you take melatonin pills, your body only absorbs about 15% of the dose into your bloodstream because most of it gets broken down before it can circulate. This means oral supplements deliver much less active melatonin to your system compared to an injection.

71%