This is how much caffeine it takes to kill an average person

A 16-year-old South Carolina teen died last month from ingesting too much caffeine, according to the Richland County coroner.

Davis Allen Cripe died from a “caffeine-induced cardiac event causing a probable arrhythmia,” according to Richland County Coroner Gary Watts. The teen ingested the caffeine from a large Diet Mountain Dew, a cafe latte from McDonald’s and an energy drink over the course of about two hours, Watts said.

While many may worry their caffeine consumption could put them at risk, the average person who drinks a cup or two of coffee has nothing to worry about.

Read: Too much caffeine caused S.C. teen's death

Here’s a look at what can happen if you drink too much coffee:

How much caffeine can I drink a day?

"Most people can safely take in about 400 milligrams of caffeine daily or about 4 cups of coffee," according to Robert Glatter, an emergency physician at Lenox Hill Hospital in New York City.

But the limit varies from person to person, Maggie Sweeney, a postdoctoral research fellow at Johns Hopkins School of Medicine's department of psychiatry.

"For adults it would be uncommon to experience effects of caffeine intoxication at less than 250 milligrams of caffeine (or 2.5 cups of coffee)," she said. "...It would typically be more than 12 ounces, but much more common to have the negative effects with greater than 500 milligrams of caffeine."

Glatter notes that children should limit caffeine consumption, and caffeine and alcohol should not be mixed.

"Mixing caffeine with alcohol is a dangerous practice because it may lead to higher levels of alcohol consumption as the person often believes and feels they are more alert," he said. "The risk of alcohol poisoning increases as people consume more alcohol because they feel the caffeine will keep them awake and alert."

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What side-effects come from drinking too much caffeine?

Glatter said the most common symptoms of excessive caffeine intake are palpitations, dizziness, elevated blood pressure, nervousness and anxiety.

"Some people also may develop diarrhea and feel like their stomach is upset as their caffeine intake increases," he said. "Not being able to sleep is another obvious symptom of consuming excess caffeine."

Everyone is different, and some may experience side effects after a cup of coffee, while others may be able to drink five cups with no issue, according to Sweeney.

"It highly varies from person to person as to how much caffeine will affect them," Sweeney said. "It can be due to speed in which our bodies process caffeine or how caffeine leaves the body – a metabolic difference."

If you are susceptible to caffeine, even a cup may cause some jitters or symptoms like nervousness or trouble sleeping, according to Sweeney. Likewise, those who increase the amount of caffeine they normally consume may also be more sensitive to coffee's negative side effects.

Sweeney notes that people might also have rambling thoughts or speech if they have consumed too much coffee.

How much coffee would it take to kill someone?

It would take a lot of K-cups, but it also varies depending on your weight.

"It would likely take anywhere from 50-100 cups of coffee to result in a lethal dose of caffeine," Glatter said. "That said, pure powdered caffeine can be lethal if a teaspoon of it is consumed at once. The recommended dose of powdered caffeine in this form is just 1/16th of a teaspoon."

Follow Mary Bowerman on Twitter: @MaryBowerman.