Study links energy drinks and stimulant supplements to increased risk of serious heart events in young adults

A new analysis presented at the American Heart Association’s Scientific Sessions in Chicago indicates that energy drinks and other stimulant-containing supplements are associated with a higher incidence of serious cardiovascular events. The retrospective observational study examined more than 28,000 FDA reports of cardiac arrest, heart attacks, ventricular arrhythmias, palpitations, rapid heart rate, chest pain and fainting. Cardiac arrest was reported about 11 times more often in cases involving caffeine- and stimulant-containing products than in reports involving products without those ingredients. Heart attacks were reported roughly 4.5 times as often, and ventricular arrhythmias or palpitations about four times as often, according to the association.

Approximately 45% of the reported events linked to stimulant products involved adults aged 18 to 34. The substances examined included caffeine, methylxanthines, guarana, yerba mate, synephrine, yohimbine and related compounds, consumed in beverages, meal-replacement shakes, protein bars, smoothies and vitamins.

"We’ve known through case reports and anecdotal evidence that caffeine in high amounts can be potentially dangerous to people with underlying heart conditions and even those who have normal hearts," said Dr. Colin Kane, pediatric cardiologist at Children’s Health and professor at UT Southwestern Medical Center.

The American Heart Association’s 2026 scientific statement notes that up to 400 mg of caffeine per day – roughly five 8-ounce cups of coffee – is generally safe for adults. However, senior study author Dr. Pamela Benavidez, a cardiothoracic anesthesiologist at Fairfield Medical Center, warned that many energy drinks contain up to three times more caffeine per fluid ounce than brewed coffee, and some pre-workout supplements contain more than 12 times as much. She added that these products often include additional stimulants such as synephrine, yohimbine and methylhexanamine, which may interact with caffeine in ways that are not fully understood, particularly in young, healthy individuals.

The researchers advise consumers, especially young adults, to monitor caffeine intake and watch for symptoms such as palpitations, chest pain, lightheadedness, fainting or irregular heartbeat during or after use. They recommend seeking medical attention if such symptoms occur and consulting a physician before using these products if a person has a known heart condition, a family history of sudden cardiac events, or takes medications that affect heart rate or rhythm.

The study’s authors note several limitations. The analysis is observational and based on voluntary FDA reports, which may be incomplete or selectively submitted. The data do not establish causation, and other factors such as alcohol, drug use, intense exercise or undiagnosed heart conditions could have contributed to the events.

"Anytime you’re mixing stimulants and other substances or medications, it can certainly bring up a potential for harm," Dr. Kane added.

The American Beverage Association responded that energy drinks have been consumed for more than three decades and are considered safe by food-safety agencies, which deem a moderate daily intake of 400 mg of caffeine safe for adults. The association also stated that energy drinks contain less caffeine than coffeehouse coffee and that no regulatory agency has found harmful interactions between caffeine and other ingredients.

Andrea Wong, chief science officer of the Council for Responsible Nutrition, cautioned that the analysis does not account for the number of consumers, usage patterns or exact ingredient amounts, making it impossible to determine the incidence or quantify the risk of cardiovascular events.