How Much Coffee Will Kill You?

We have written a lot about healthy organic coffee and the health benefits of coffee in general. There are a lot of good reasons to drink coffee and it turns out that many of those benefits increase as you drink more cups each day. However, caffeine is a stimulant that can give you the shakes if you consume too much. Like most substances there is a limit to how much is good and when it turns bad. So, how much coffee will kill you? Let’s start with what the Mayo Clinic says about how much coffee is too much.

Using caffeine to mask sleep deprivation can create an unwelcome cycle. For example, you may drink caffeinated beverages because you have trouble staying awake during the day. But the caffeine keeps you from falling asleep at night, shortening the length of time you sleep.

And some medications like the antibiotics ciprofloxacin and norfloxacin interact with caffeine and interfere with its breakdown in the body. The anti-asthma drug theophylline will build up in your system because caffeine interferes with its breakdown. And if you drink coffee and use the herbal supplement Echinacea your caffeine level will build up.

But, aside from when to drink coffee and use these substances how much coffee is enough and how much is too much. 400 milligrams of caffeine, about the amount in four cups of brewed coffee is OK for most adults but adolescents should consume only a fourth this amount. If you drink too much these things happen:

  • Insomnia
  • Nervousness
  • Restlessness
  • Irritability
  • Stomach upset
  • Fast heartbeat
  • Muscle tremors

But how much coffee will kill you? Popular Science reports on the death of a 14-year-old and discusses how much caffeine would it take to kill you.

Jack James, the editor-in-chief of the Journal of Caffeine Research, says that overdose for adults requires roughly 10 grams of caffeine. (People typically ingest just 1 to 2 mg/kg of caffeine per beverage.) A 2005 Forensic Science International article on two fatal caffeine overdoses in New Mexico pegs the figure closer to about 5 grams–an amount that would still require drinking more than 6 gallons of McDonald’s coffee. Whereas a normal cup of coffee might bring the concentration of caffeine in your plasma to 2.5 to 7 mg/L, the two people who died in New Mexico–a woman who might’ve used caffeine to cut intravenous drugs, and a man whose family said he ingested a bottle of sleeping pills–both had concentrations 100 times higher. (A web application called “Death By Caffeine” uses a benchmark around 6 grams per hundred pounds of body weight to estimate death, but it’s “for entertainment purposes only.”)

So, you would need to drink gallons of McDonald’s coffee to do yourself in. What else is involved? The Popular Science article mentions that one girl who died of a caffeine overdose had a pre-existent cardiac condition and was prone to heart rhythm disturbances. The caffeine in that case likely provoked the underlying disease causing her death.

How Fast You Drink It

Sleep Education notes whatever amount of caffeine you have in your system, half of it is gone in three to five hours. When you drink coffee it absorbs and reaches a peak level in thirty minutes to an hour. To kill yourself with an overdose of coffee you would need to drink all of your ten gallons in a hour. It you spread it out over many hours you will already be getting rid of the first that you drank as you consume the last.


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