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Caffeine Side Effects

How much caffeine is too much?

“Too much” can vary from person to person, depending on factors such as body weight, medication intake, and individual sensitivity.

  • For most healthy adults, the FDA cites 400 mg of caffeine a day is not generally associated with dangerous side effects.

  • 400mg of caffeine is about four cups of brewed coffee or eight cups of tea per day.

  • The FDA has not set a level for children, but the American Academy of Pediatrics is not keen on kids drinking caffeinated beverages or other stimulants.

But I drink decaf…

Decaffeinated drinks have less caffeine but are not caffeine-free.

  • An 8oz cup of decaf coffee has about 2 to 15 mg of caffeine.

Caffeine-sensitive individuals need to consider the caffeine in decaf drinks when tabulating their tolerable daily allowance.

So, what are some signs that I’ve had too much caffeine?

Caffeine overdose can cause seizures. Most people will not risk such toxic effects by chugging 1,200 mg of caffeine in a short period of time.

But, simply drinking too much caffeine can lead to undesirable side effects such as:

  • Restlessness and shakiness

  • Insomnia

  • Headaches

  • Anxiousness

  • Fast heart rate

  • Upset stomach

  • Nausea

  • Dizziness

Okay, I’m ready to cut back

Great. Do so gradually.

To avoid caffeine withdrawal, consider:

  • Figure out how much caffeine your body can tolerate. One review finds that intake of 2.5 mg caffeine/kg of body weight per day is not associated with undesirable effects.

  • Keep tabs. Pay attention to how much caffeine is in food and beverages.

  • Cut back gradually.

  • Drink decaf.

  • Shorten the brew time or go herbal.


Harvey S, Urban J, Doepker C. Systematic review of the potential adverse effects of caffeine consumption in healthy adults, pregnant women, adolescents, and children. Food Chem Toxicol. 2017

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