Cardiac Arrest Reports Were About 11 Times More Common With Energy Drinks, Study Finds

Caffeinated energy drinks and stimulant supplements turned up far more often in reports of serious heart problems than other foods and supplements did, according to a new analysis of U.S. government safety data. The pattern was strongest for cardiac arrest and heart attack, and many of the reports involved adults ages 18 to 34, a group not usually seen as high risk for heart disease.

The findings, announced by the American Heart Association on Nov. 2, are preliminary. They come from a research abstract that has not been peer-reviewed, and they will be presented at the association's Scientific Sessions in Chicago, Nov. 6-9. The study also cannot show that these products cause heart events.

The central numbers from the analysis

• More than 28,000: The number of adverse-event reports to the FDA that researchers reviewed, covering 2017 to 2025. The data included people 13 or older.
• About 11 times: How much more often cardiac arrest was reported with caffeine- and stimulant-containing products than with products lacking those ingredients.
• About 4.5 times: How much more likely reports involving energy drinks and supplements were to include heart attacks.
• Four times: The higher likelihood that those reports included ventricular arrhythmias, which are abnormal rhythms in the heart's lower pumping chambers, or heart palpitations.
• About 45%: The share of reports linking these products to cardiovascular events that involved adults ages 18 to 34.
• Nearly 3 times, 2.71 times and about 2 times: The higher frequency of reports of elevated heart rate, chest pain and fainting, respectively.

How the comparison was made

The researchers used a government safety database to compare reports tied to caffeine- and stimulant-containing products with reports tied to other FDA-regulated foods and dietary supplements. The comparison group included soft drinks, meal replacement shakes, protein bars, smoothies and vitamins. Similar patterns showed up in reports involving both men and women, according to the American Heart Association.

The study measures how often heart problems appear in reports tied to certain products. It does not measure how many people who use the products have heart events.

Why the young adult pattern is unclear

Researchers said they do not fully understand why young adults featured so prominently. The association suggested several possible explanations: how often young adults consume these products, when and how they use them, and whether some have an undiagnosed heart condition. Examples of use that the association gave were drinking them before intense exercise or mixing them with alcohol or drugs.

Gregory M. Marcus, M.D., who chaired the association's 2026 scientific statement on caffeine and cardiovascular disease, said the study raises concern that products with very high caffeine levels may harm the cardiovascular system. He said there are biological reasons such a connection is plausible, but that the study does not prove caffeine products cause these events.

What it means for people who drink energy drinks or take stimulant supplements

Sales of caffeinated energy drinks have more than doubled over the past decade, reaching over $20 billion in 2024, according to the association. The products are often sold next to soda and bottled water. Study author Sai Samayamanthula, a fourth-year medical student at the University of Virginia School of Medicine, said that is one reason many people assume they carry no real risk.

Samayamanthula said that for many healthy people who use these products only occasionally, the risk is probably small. He said people who use them regularly can quickly exceed the recommended daily caffeine limit.

That limit comes from the association's 2026 scientific statement. It says up to 400 mg of caffeine a day, the equivalent of up to 5 eight-ounce cups of regular black coffee, is generally safe for most adults. The association said some energy drinks contain as much as 3 times more caffeine per fluid ounce than brewed coffee. Some pre-workout supplements contain more than 12 times as much per fluid ounce.

The FDA regulates energy drinks and stimulant supplements as foods or dietary supplements, not as medications. As a result, they do not go through the premarket safety testing that medications must pass, according to the association.

Samayamanthula also said doctors should ask younger patients who have palpitations, chest pain or fainting spells whether they recently or regularly consume these products.

What comes next

The researchers said more studies are needed to understand the relationship between caffeinated products and cardiovascular conditions. They also called for more systematic safety monitoring of these products. The findings are considered preliminary until they are published as a full manuscript in a peer-reviewed journal.

Around Prague, based on reporting by www.heart.org