An analysis of medical data from more than 130,000 adults in the US and UK found that people who took melatonin as prescribed for more than a year had an 89% higher risk of heart failure over five years than those who did not take it. They were also nearly twice as likely to die from any cause (7.8% vs. 4.3%) and 3.5 times more likely to be hospitalized for heart failure.
The authors emphasize that the results have not yet been peer-reviewed and do not prove a direct cause-and-effect relationship. Additionally, the study was based on prescription data rather than actual drug use, which may have affected the accuracy of the findings.
Melatonin is considered safe for short-term use (up to 1–2 months) and is widely available over the counter in many countries. However, scientists note that its long-term effects have not been sufficiently studied and require additional clinical research.
