Caffeine has benefits in small doses, like increased alertness and boosted exercise performance, but too much can cause jitters, exacerbate anxiety, and mess with your sleep schedule. Another downside to getting too much of a caffeine buzz? Changes in heart rate and even arrhythmia, a condition when your heartbeat becomes too fast, too slow, or beats irregularly. (Related: Why Caffeine Is The Best Thing That's Ever Happened to Your Workout)
While arrhythmias can be benign and research has indicated that moderate caffeine intake (a.k.a. one to three cups of coffee per day) doesn't *really* increase your risk, going way overboard on coffee, soda, or energy drinks can lead to a phenomenon called caffeine-induced cardiac arrest, which essentially means your heart stops beating and can be fatal. That's what happened last month when 16-year-old Davis Allen Cripe drank a large Mountain Dew, a latte from McDonalds, and an energy drink all within a two-hour time period. Cripe tragically collapsed and died in his high school classroom. You know that you shouldn't consume unlimited amounts of caffeine, but most people probably don't think about the fact that a serious coffee, soda, or energy drink habit has the potential to kill you under some rare but scary circumstances.
Though this sounds terrifying, experts say there's no need to worry as long as you're keeping your caffeine intake in check. "The likelihood of having a caffeine-related cardiac event is extremely small," says Jennifer Haythe, M.D., a cardiologist, assistant professor of medicine at Columbia University, and co-director of the Center for Women's Cardiovascular Health. This is especially true if you're staying within the recommended limit of 400 milligrams of caffeine per day (about 3 to 5 cups of brewed coffee depending on the strength).
Plus, the level of risk is different for everyone, says cardiologist Monali Y. Desai, M.D. "Research has shown that some people are slow metabolizers of caffeine, and their risk of cardiac events would be expected to go up the more caffeine they have," says Desai. "That being said, the average person doesn't need to be concerned with drinking caffeine too quickly unless they're drinking 600 mg or more of caffeine every day or they're concerned they're a slow metabolizer." If you notice that caffeine affects you substantially, she recommends speaking with a gastroenterologist about how your body really is digesting and absorbing the caffeine. (Side note: Here's how to give up caffeine and become a morning person.)
In general, the people who need to be the most careful (about going over the daily recommended limit) are ones who have a family or personal history of heart problems. "But studies have shown no negative cardiac effects for the average person with six or fewer cups of coffee a day (roughly less than 600 mg of caffeine)," says Desai. She does note that there are always exceptions, though. If you have a history of abnormal heart rhythms, you should definitely discuss *any* caffeine intake with a cardiologist, she says.
According to the medical examiner on Cripe's case, his death was likely a result of consuming so much caffeine in such a short amount of time, especially since an autopsy didn't uncover any undiagnosed heart conditions. If you're wondering how much time you should have between lattes, Haythe suggests one to two hours between caffeinated drinks. She also advises limiting excessive caffeine overall. And if you do drink a ton of caffeine in succession, "watch for symptoms like palpitations, dizziness, lightheadedness, shortness of breath, and chest pain. If you develop any of these signs, seek medical attention as soon as possible," she says.
As of now, it looks like there's no reason to kick your caffeine habit completely (unless you want to, of course!), but it's important to be mindful of how much and how quickly you're drinking it, and when in doubt, check with your doc about the amount that's right for you.