In April, a 16-year-old in South Carolina died from overdosing on caffeine, CNN reports. The otherwise healthy teenager, Davis Allen Cripe, reportedly drank a McDonald's latte, a large Mountain Dew, and an unnamed energy drink in a two-hour span, and then collapsed. The caffeine overdose prompted a “caffeine-induced cardiac event causing a probable arrhythmia," according to the coroner's report. In other words, too much caffeine prevented his heart from pumping enough blood to his brain and other vital organs. Exactly how much caffeine can cause an overdose like this? And how often do people die from a caffeine overdose?

It's becoming easier than ever for people to accidentally overdose on caffeine, as it appears in everything from gummy candies to energy drinks to powders. Not to mention, extra-caffeinated coffees are all the rage, with companies using a "dangerous amount of caffeine" as a selling point. 

Caffeine, while legal, is a drug, and like any drug, its effects are different for everyone. This means that the daily recommended maximum amount of caffeine—400 milligrams for adults and 100 milligrams for children 12-18—can be way too much for some people, especially when consumed rapidly. The body simply cannot metabolize caffeine at the rate it needs to. 

The number of people who die every year from a caffeine overdose isn't well reported, likely because it happens so rarely. In addition, many times caffeine only plays a partial role: It's often when a lot of caffeine is combined with other substances or heart conditions that it can be deadly. In 2013, the American Association of Poison Control Centers tracked reported overdoses from caffeine and energy drinks that contain caffeine (meaning they may include other compounds, like taurine). Of the 4,201 reports, 2,751 were people under the age of 20. Fortunately, there were no reported deaths.

Dying from a caffeine overdose is so rare that South Carolina's coroner had never previously witnessed it in his state. The coroner and Cripe's parents are using the tragedy to talk about the dangers of too much caffeine, especially from popular energy drinks that are so often marketed to young people. "We lost Davis from a totally legal substance," the coroner said. "These drinks can be dangerous."