A review of more than 28,000 federal safety reports found substantially higher reporting rates of serious cardiovascular events involving products containing caffeine and other stimulants, particularly among adults ages 18 to 34.
By yourNEWS Media Newsroom
DALLAS — Energy drinks and dietary supplements containing caffeine and other stimulants were associated with disproportionately high reports of cardiac arrest, heart attacks and dangerous heart rhythms, according to preliminary research announced by the American Heart Association on Nov. 2.
Researchers examining federal safety data found that cardiac arrest appeared approximately 11 times more frequently in adverse-event reports involving stimulant-containing products than in reports involving products without those ingredients. Heart attacks were reported about 4.5 times more frequently, while ventricular arrhythmias and heart palpitations appeared approximately four times more often.
The findings, detailed in an American Heart Association research announcement, are scheduled for presentation at the organization’s Scientific Sessions 2026, held Nov. 6-9 in Chicago.
The study analyzed 28,345 adverse-event reports submitted to the U.S. Food and Drug Administration between 2017 and 2025. Of those, 854 involved caffeinated energy drinks or stimulant-containing dietary supplements, while 27,491 concerned products without those ingredients.
Approximately 45% of the cardiovascular event reports associated with stimulant products involved adults ages 18 to 34, a population generally considered at lower risk for serious heart problems.
Researchers also found that elevated heart rates appeared nearly three times more frequently in reports involving stimulant products, chest pain approximately 2.7 times more often and fainting about twice as frequently.
Similar reporting patterns appeared among men and women.
Sai Samayamanthula, a fourth-year medical student at the University of Virginia School of Medicine and an author of the research, said consumers may underestimate the potential risks because energy drinks are widely available alongside ordinary beverages.
“These products are marketed as everyday pick-me-ups and sold next to soda and bottled water, so most people assume they carry no real risk,” Samayamanthula said.
He emphasized that occasional consumption may carry relatively little risk for many healthy adults, but frequent use can result in excessive caffeine exposure.
“For many healthy people, if these products are consumed occasionally, the risk is probably small. However, individuals who consume energy drinks or other stimulant-containing supplements regularly can quickly exceed the recommended daily limit for caffeine, so it’s important for people to know that there may be a risk of cardiovascular harm with these products.”
The investigation examined several categories of stimulant ingredients, including caffeine, guarana, yerba mate, green tea and coffee extracts, synephrine, yohimbine, ephedra, DMAA and higenamine.
Researchers grouped products according to their ingredients rather than individual brands, meaning the findings did not establish that any particular manufacturer or product was responsible for the reported events.
The analysis also included adverse reactions associated with other foods and dietary supplements, such as soft drinks, protein bars, meal replacement shakes, smoothies and vitamins.
One concern identified by researchers was the concentration of caffeine in some commercially available products.
According to the American Heart Association, certain energy drinks contain as much as three times more caffeine per fluid ounce than brewed coffee, while some pre-workout supplements contain more than 12 times as much.
The association’s 2026 scientific statement on caffeine and cardiovascular disease concluded that consuming up to approximately 400 milligrams of caffeine daily is generally safe for most healthy adults.
However, individual responses vary, and people with certain medical conditions, medication interactions or heightened caffeine sensitivity may need lower amounts.
The potential cardiovascular effects of concentrated stimulants have attracted growing attention as the energy drink industry expands.
American energy drink sales exceeded $20 billion in 2024, more than doubling over the preceding decade, according to figures cited by the researchers.
Consumers frequently use these products to increase alertness, improve athletic performance or combat fatigue.
Some individuals also combine energy drinks with alcohol, other stimulants or intense physical activity, circumstances that may complicate their physiological effects.
Researchers said those consumption patterns could partly explain why younger adults appeared so frequently in the adverse-event reports.
Other possible contributing factors include underlying heart conditions that had not previously been diagnosed.
The researchers emphasized that their findings do not establish that energy drinks or supplements caused the cardiovascular events.
The FDA database relies on reports submitted by consumers, health professionals and manufacturers. Researchers do not know how many people consumed the products without experiencing complications or how many adverse events went unreported.
Consequently, the analysis cannot determine the actual likelihood of a consumer experiencing cardiac arrest, a heart attack or another cardiovascular condition after using these products.
Gregory M. Marcus, a professor of medicine at the University of California, San Francisco, and chair of the American Heart Association’s 2026 caffeine scientific statement, cautioned against interpreting the associations as proof of causation.
“This study raises concerns that products with very high amounts of caffeine may be harmful to the cardiovascular system,” Marcus said.
“Although there are biological reasons why that connection could be possible, the study does not prove that caffeine products cause these events, because other factors may have influenced the results found in this analysis. More research is needed to understand whether these stimulant products are truly responsible for the reported heart-related events.”
The findings also prompted a response from the dietary supplement industry.
In a statement addressing the preliminary research, the Council for Responsible Nutrition questioned the comparison of products containing different stimulants, dosages and formulations.
The organization argued that adverse-event reports cannot establish whether the products caused the reported medical problems or determine the risk to consumers.
It also noted that some substances included in the analysis cannot legally be marketed in conventional dietary supplements.
Unlike prescription medications, energy drinks and most dietary supplements generally do not undergo FDA premarket approval demonstrating safety and effectiveness.
Manufacturers are responsible for meeting applicable federal safety requirements, while regulators can take enforcement action against products containing prohibited ingredients or presenting safety concerns.
The American Heart Association researchers recommended more systematic monitoring of stimulant-containing products and additional studies examining their effects on cardiovascular health.
Samayamanthula also urged clinicians to ask younger patients experiencing unexplained heart symptoms about their consumption of energy drinks and supplements.
“Our findings support the case for more systematic safety monitoring of caffeine- and stimulant-containing products,” he said.
“In addition, healthcare professionals should remember to ask their younger patients who have palpitations, chest pain or fainting spells if they recently or regularly consume these products.”
The research has not yet undergone full peer review, and its conclusions remain preliminary pending publication in a scientific journal.
Nevertheless, the findings highlight the importance of examining caffeine exposure from multiple sources, particularly when concentrated energy drinks and workout supplements are consumed together.
The researchers concluded that further investigation is needed to establish whether specific stimulant ingredients, combinations or consumption patterns contribute directly to serious cardiovascular events, especially among younger adults.
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