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May 23, 2017

Caffeine overdoses are rare—but they're not impossible. Here are the risks.

Daily Briefing

The recent passing of Davis Allen Cripe, a teenager who died suddenly from a "caffeine-induced cardiac event," has spurred concerns about the dangers of consuming too much caffeine. In the wake of Cripe's passing, experts have reiterated that caffeine remains a relatively safe indulgence—but there are still risks.

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The benefits and risks of caffeine

According to research, roughly 90 percent of adults in the world drink caffeine—through tea, coffee, soda, and other beverages. Vox's Julie Belluz writes that people in the United States average around two cups of coffee per day, which equals anywhere from 100 to 200 mg of caffeine. In comparison, a can of soda will usually have less than 70 mg of caffeine, while an energy drink will have anywhere from 50 to 300 mg of caffeine.

Caffeine, Belluz writes, is associated with numerous health benefits. It stimulates the central nervous system, boosts alertness, improves cognitive performance, and can even improve short-term memory. The drug also has been linked to a lowered risk for cardiovascular disease and Type 2 diabetes.

But too much caffeine can trigger some negative side effects, such as jitteriness, insomnia, irritability. Caffeine also "can speed up the heart beat and disturb the body's blood flow—which, in extreme cases, can be fatal," Belluz writes.

How much caffeine is too much?

According to Belluz, the maximum recommended dose of caffeine is 400 mg per day for an adult, and 100 mg per day for kids ages 12 to 18—though caffeine tolerance may vary by the individual. For instance, those with underlying health problems or on certain medications may have a lower tolerance than others. Genetics also can play a role.

Generally, caffeine can reach toxic levels at around 30 or more cups of coffee in a short amount of time. At these levels, symptoms will get more serious, including vomiting, abdominal pain, altered consciousness, and seizures. When death does occur, it's typically  because of ventricular fibrillation, an irregular and rapid heartbeat that disrupts the blood flow, causing low blood pressure, loss of consciousness, and—eventually—death.

But experts say those types of deaths are rare, particularly from beverages alone. According to one research review, there were only 45 such deaths between 1959 and 2010. A 2017 study spotted 51 such deaths, but also noted that the caffeine levels in the blood of the deceased individuals were "incredibly high," Belluz writes. Someone who's had one cup of coffee might have caffeine blood levels of about 5 or 6 mg/L—the caffeine blood levels of those who died from a caffeine overdose, according to the study, had levels of 180 mg/L.

And while energy drinks, which typically have more caffeine than coffee, might make it easier to overdose, it would still be quite difficult, Belluz writes, because someone would have to drink 10 highly caffeinated energy drinks in short succession to be in any serious danger of a caffeine overdose.

The real danger of energy drinks, she explains, comes from the fact that they include other stimulants, such as guarana, taurine, and L-carnitine. These combinations can become particularly dangerous when mixed with alcohol.

Powdered caffeine–the real danger

But data show caffeine supplements, such as powdered caffeine, pose the greatest risk. According to FDA, a single teaspoon of caffeine powder is roughly equivalent to 28 cups of coffee—meaning just one teaspoon is potentially fatal.

Further, the 2017 study found that half of caffeine-related deaths were suicides, and all of those involved consuming powdered or tablet form of caffeine. In turn, Alex Wayne Jones—a toxicologist with Linköping University in Sweden and lead author of the study—concluded that it's unlikely that "toxic concentrations of caffeine can be achieved from over-consumption of caffeinated beverages alone."

Consuming in small doses

"I think it's important to be aware, that caffeine is generally safe in the doses most people consume," said Jeffrey Goldberger, a University of Miami cardiologist and expert on the effects of caffeine. "But it does have the potential to be dangerous at extremely high doses, and there are people who have some sensitivities to it."

In fact, Goldberger estimated that Cripe probably only ingested about 500 mg of caffeine, based on the descriptions of his consumption, making it unlikely to be lethal. Goldberger hypothesized that Cripe had another unrecognized health issue, or perhaps was one of the rare few who pass suddenly at a young age.

"The bottom line," Belluz writes, is that "if you stick to regular coffee, tea, and the odd energy drink—and avoid chugging these beverages in Herculean doses—you should be just fine" (Belluz, Vox, 5/17; Haelle, Forbes, 5/16).

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