Does Taking Melatonin Raise Your Risk of Heart Failure?

In the United States, melatonin is one of the most common sleep aids available without a prescription. It’s sold as an over-the-counter dietary supplement. However, in other countries, such as the United Kingdom and Japan, people need to be prescribed melatonin for chronic sleep problems.

In the short term, melatonin is generally considered safe to take for occasional sleep issues. But is it OK to take melatonin long-term, and does it increase your risk for certain medical conditions like heart failure?

Melatonin and Heart Health

An abstract presented at the 2025 American Heart Association Scientific Sessions shared how melatonin can affect your health — specifically your heart health. This research raised questions about whether long-term melatonin use might be linked to heart disease or heart failure.

The preliminary study analyzed health records of people with insomnia and compared a melatonin group — people who took melatonin long-term (12 months or more) — to a control group of people who did not take melatonin.

In the main analysis, scientists found a 90% increase in heart failure in people with chronic insomnia who took melatonin for five years, compared with people who had insomnia but did not take melatonin.

Although scientists reported a higher risk of heart failure in people using melatonin long-term, the data is considered preliminary — meaning the findings are still early and have not yet been confirmed by additional studies.

“The study was retrospective, which means the data was already collected and then reviewed. There may be other differences and risk factors in that group that are not accounted for,” says Northwestern Medicine Cardiologist Micah J. Eimer, MD. “We need a prospective trial next to really assess whether people who take melatonin have more heart problems than people who don’t take it.”

It’s possible that insomnia itself — or another health condition that causes insomnia — could explain the findings. To truly understand whether melatonin increases the risk of heart failure, scientists would need to conduct future studies that look at whether dosage, duration of use or interactions with common heart medications play a role in cardiovascular outcomes.

“More studies are needed to determine how it impacts people with heart disease,” says Dr. Eimer.  

Why Might Melatonin Affect Heart Health?

Scientists are exploring how melatonin interacts with receptors throughout the body, including in the cardiovascular system. It’s thought that melatonin may influence blood pressure or heart rhythm, but these effects are not yet fully understood.

Dosage and duration may also matter. Long-term melatonin use could have different effects than short-term use. Long-term use is defined by taking it longer than 12 months.

Who Is Most at Risk When Taking Melatonin?

When taking melatonin or any new supplement, some people may be more at risk, including:

• People with an existing heart failure diagnosis
• Adults older than 65, as age often brings additional health concerns and a higher likelihood of taking multiple medications
• Individuals with multiple risk factors for heart disease, such as:
• Diabetes
• High blood pressure
• High cholesterol

People in these groups may not only be taking melatonin, but also other supplements or prescription medications. This increases the potential for medication interactions, which can affect:

• Heart rhythm
• Blood pressure
• How well specific medications work

For example, melatonin may interact with beta-blockers (medications that slow your heart rate and lower your blood pressure) or anticoagulants (blood thinners) because it may increase the risk of bleeding.

While current evidence does not conclusively link melatonin to heart failure, talk to your primary care physician before taking any new supplement, including melatonin. Share a complete list of medications and supplements to help your doctor assess possible risks.

Why Aren’t Melatonin Supplements Regulated?

Because melatonin is considered a dietary supplement in the United States, it’s not regulated by the U.S. Food and Drug Administration (FDA). That means dosage and purity can vary widely between brands.

If you do decide to take melatonin, look for supplements that are verified by a third-party testing organization, such as U.S. Pharmacopeia (USP). A verified mark on the label can indicate that the supplement meets quality and purity standards. You can also use websites or other resources that review supplements to help you choose a trustworthy brand.

Also, start by taking the lowest effective dose of melatonin. Most adults begin with 0.5 to 1 milligram taken 30 minutes before bedtime.

Additional Ways to Get Better Sleep Without Melatonin

You can improve your sleep quality by practicing good sleep hygiene. Establish healthy sleep habits, including:

• Getting seven to nine hours of sleep each night
• Establishing a consistent sleep schedule by going to bed and waking up at the same time every day
• Avoiding caffeine six to eight hours before bedtime
• Turning off screens at least one hour before bed, since blue light from devices can suppress your body’s natural production of melatonin
• Creating a calming bedtime routine, such as reading or doing breathing exercises or gentle stretching
• Setting your room temperature to about 65 degrees Fahrenheit
• Wearing a sleep mask or using blackout shades to block light from interrupting your sleep
• Finding a sleeping position that works for you

Making an Informed Decision About Taking Melatonin

Until more research on cardiovascular safety is available, it’s best to use melatonin in moderation and with medical guidance — especially if you have a higher risk of cardiovascular disease.

Talk to your doctor before adding melatonin — or any new supplement — to your routine.