A new study presented at the American Heart Association’s 2025 Scientific Sessions suggests that long-term prescription melatonin use could be associated with a higher risk of heart failure, hospitalization, and death.

While the findings are attention-grabbing, experts say they’re preliminary and don’t prove that melatonin directly causes heart problems.

Study Finds Higher Risk Among Long-Term Users

The five-year study tracked 130,828 adults with insomnia and found that people who took prescription melatonin for at least one year had a 90% higher chance of heart failure. Researchers analyzed data from the United States and the United Kingdom. While melatonin is available over-the-counter in the U.S., it’s prescription-only in the U.K.

Since the “melatonin” group in the study only included people who had been prescribed melatonin, it did not account for OTC use.

Since this was an observational study, it does not prove that melatonin directly caused heart failure. More studies, including gold-standard randomized controlled trials, are needed to validate these findings.

The new findings did not explain why melatonin may harm the heart. People who take melatonin long-term may have stress or sleep-related issues that actually cause heart failure.

“It may not necessarily be the melatonin, but it’s just the fact that sleep is extremely important and necessary for not just cardiovascular health, but overall health and well-being,” said Tochukwu M. Okwuosa, DO, FACC, FAHA, a cardiologist and a professor of internal medicine at Rush University, who was not involved with the study.

Why Long-Term Melatonin Use Isn’t Recommended

Estimates suggest that 5 million U.S. adults and 4 million U.S. children take melatonin each month, making it one of the most commonly used sleep aids. Its perceived safety and accessibility have driven growing use in recent years. These new findings underscore the importance of talking with a healthcare provider before using melatonin for an extended period.

Anyone who relies on melatonin nightly should consider seeing a sleep specialist to determine potential underlying issues like chronic insomnia or stress, Okwuosa said. People who don’t get enough sleep have a higher risk of high blood pressure, heart disease, and stroke.

Short-term melatonin use can help with certain sleep issues and may offer some cardiovascular benefits. Human and animal studies have suggested that melatonin can help relieve oxidative stress and improve left ventricular function in people with heart failure.

“If a patient is taking melatonin for a few days or a few weeks, I would not have any problems with it,” Okwuosa said.

Are There Alternatives to Melatonin?

Short-term melatonin use is generally safe, but it may interact with certain medications or cause daytime drowsiness, nausea, dizziness, or headaches in some people.

“The long-term implications of melatonin are unclear, and more studies should be done. At this time, I would recommend using it at the lowest dose possible, and for the shortest duration possible,” Jamie Alan, RPh, PharmD, PhD, an associate professor of pharmacology and toxicology at Michigan State University, told Verywell in an email.

There are other medications, such as Benadryl (diphenhydramine) and Ambien (zolpidem), that can help with sleep. Talk with your healthcare provider if you are worried about melatonin or interested in these other medications, since they also come with risks, Alan added. Cognitive behavioral therapy for insomnia may help address sleep problems without long-term medication use.