Is long-term melatonin use safe? New study highlights heart risks
The long-term use of melatonin supplements is associated with a heightened risk of heart failure, according to new data presented at the American Heart Association’s Scientific Sessions 2025 conference. Adults with insomnia regularly take melatonin to help them sleep.
The study’s authors explored data from the TriNetX Global Research Network, a large international database, on more than 130,000 adult patients with insomnia who used melatonin for at least one year. Overall, the use of melatonin was linked to a 90% higher chance of developing heart failure over a five-year period.
In addition, heart failure hospitalization rates were 19% for melatonin users and 6.6% for non-users. All-cause mortality rates, meanwhile, were 7.8% for melatonin users and 4.3% for non-users.
“Melatonin supplements may not be as harmless as commonly assumed,” lead author Ekenedilichukwu Nnadi, MD, a chief resident in internal medicine at SUNY Downstate/Kings County Primary Care in Brooklyn, New York, said in a statement. “If our study is confirmed, this could affect how doctors counsel patients about sleep aids.”
Marie-Pierre St-Onge, PhD, a professor of nutritional medicine at the Columbia University Institute of Human Nutrition who specializes in cardiovascular disease prevention, noted in the same statement that the long-term use of melatonin is not recommended.
“I’m surprised that physicians would prescribe melatonin for insomnia and have patients use it for more than 365 days, since melatonin, at least in the U.S., is not indicated for the treatment of insomnia,” St-Onge, chair of the writing group for the American Heart Association’s 2025 scientific statement on sleep health, explained. “In the U.S., melatonin can be taken as an over-the-counter supplement and people should be aware that it should not be taken chronically without a proper indication.”
Researchers did note that more research is still necessary to confirm that melatonin is directly leading to these increased risks.
“While the association we found raises safety concerns about the widely used supplement, our study cannot prove a direct cause-and-effect relationship,” Nnadi said.
The American Heart Association’s Scientific Sessions 2025 conference runs Nov. 7-10 in New Orleans. Click here for additional details.
Michael has more than 19 years of experience as a professional writer and editor. He has written at length about cardiology, radiology, artificial intelligence and other key healthcare topics.