A new American Heart Association scientific statement says that for most adults, consuming up to 400 milligrams of caffeine a day—about the amount in up to five 8‑ounce cups of caffeinated coffee—appears generally safe and may be linked to lower risks of some cardiovascular conditions. The statement cautions, however, that higher-dose products such as energy drinks and energy shots may raise blood pressure and increase the likelihood of irregular heart rhythms.
A scientific statement from the American Heart Association (AHA), published July 20, 2026 in Circulation, reviewed recent research on caffeine and cardiovascular health and concluded that, for most adults, intake of up to 400 milligrams of caffeine per day—roughly up to five 8‑ounce cups of caffeinated coffee—“is safe and does not increase cardiovascular risk.” The statement added that this level of intake may also be associated with lower risks of heart failure, heart disease and stroke for some people.
The AHA emphasized that evidence from studies of caffeinated coffee “consumed in normal amounts” should not be assumed to apply to caffeinated energy drinks. In the statement’s summary, higher caffeine consumption—particularly amounts found in energy drinks and energy shots—was linked with a greater likelihood of high blood pressure and irregular heart rhythm (arrhythmia). It also noted that very high doses, such as those in energy drinks and shots, have been associated with abnormal heart rhythms even among people considered at low cardiovascular risk, including healthy adults under 30.
Gregory M. Marcus, chair of the AHA writing group and a professor at the University of California, San Francisco, said individuals can respond very differently to caffeine depending on factors such as age, medications, underlying health conditions and genetics. What is tolerable for one person, he said, may cause symptoms such as heart palpitations, anxiety or sleep disruption in another.
The review also reported that drinking 2 to 4 cups of caffeinated coffee per day was associated with lower risks of heart disease, heart failure and stroke, but it cautioned that the relationship may change at higher levels; consuming more than four cups daily was described as potentially increasing heart-failure risk.
Researchers called for more randomized controlled trials to better clarify how caffeine affects cardiovascular health, why people respond differently, and how risks and benefits vary across coffee, tea, soda, energy drinks, energy shots and other caffeine products. Because evidence for energy drinks and other newer high-caffeine products remains limited, the AHA noted that caffeine was not included in the organization’s 2026 dietary guidance for cardiovascular health.
The statement did not quantify how much more caffeine per ounce energy shots contain compared with coffee, and it did not conclude that adding milk or sugar “reduces” coffee’s cardiovascular benefits; instead, it highlighted that energy drinks and related products may include additional ingredients that can speed caffeine absorption and potentially intensify short-term cardiovascular effects.
