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A Washington state man celebrated his birthday this year by treating himself to the most expensive drink you can custom-order at Starbucks. Let's hope he didn't chug that toxic — and potentially lethal — dose of caffeine in one sitting. 

A Seattleite named Beau Chevassus is today's Internet hero for ordering a Quadriginoctuple Frappucino, the unofficial name for a 52-ounce Venti with no less than 48 shots of espresso, all garnished with every carmel-fructose-mocha-syrup topping that Starbucks keeps behind the counter. The total for this caffeine bomb cocktail set Chevassus back $47.30 (which more than doubles the old record for most expensive Starbucks drink, a miserly total of $23.60). His extravagant coffee binge is the talk of the local TV news circuit

Congratulations to Chevassus for his historic achievement, but perhaps he should've added a "don't try this at home" disclaimer to his viral video. Because his stimulating concoction contains enough caffeine to put drinkers well over the threshold for caffeine toxicity, and even approaches potentially lethal territory. By Starbucks' own estimates, one shot of espresso contains about 75 milligrams of caffeine. Multiply that by 48 and you get a drink that packs a whopping 3.6 grams of caffeine. 

The science of caffeine overdose is tricky, considering the Herculean feats of coffee consumption required to put caffeine fiends in critical condition. But overdoses have occurred. Even a handful of deaths. From these few cases, doctors like Cleveland Clinic cardiac surgeon Marc Gillinov have been able to determine that 1 gram of caffeine is enough to cause caffeine toxicity, which leads to abnormal heart functioning and cardiac arrest in some cases. The U.S. National Institutes of Health website warns that "in severe cases" such overdoses can lead to death via "convulsions or an irregular heartbeat." The Quadriginoctuple Frappucino contains well over triple that caffeine threshold.

As for surely-fatal doses, the Journal of Caffeine Research's editor-in-chief Jack James tells Popular Science's Sam Eifling that 10 grams of caffeine would be enough to send drinkers jittering into the great beyond. The Quadriginoctuple Frap contains just over a third of that, but other research suggests it comes much closer to packing a fatal dose. A 2005 study conducted by the New Mexico Department of Health following two caffeine-related deaths concluded that 5 grams is enough to prove deadly. And indeed, a British man died in 2010 from ingesting about 5.6 grams of caffeine powder. Even less caffeine has reportedly taken lives in anecdotal cases. According to parents who claim their 14-year-old daughter died from drinking two 24-ounce Monster energy drinks in a 24-hour period, 480 mg was enough to end her life. The Quadriginoctuple Frappucino exceeds that seven times over. 

However, as long as you aren't guzzling down dozens of cappuccinos through a beer bong or anything like that, you should be fine. Talking with CBS News' Michelle Castillo, Dr. Gillinov recommends not exceeding more than 400 to 500 milligrams of caffeine (or about two small cups of coffee) per day. 

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