Harvard Health Letter

Caffeine IQ: How much is too much?

A safe amount of caffeine intake each day is 200 to 300 milligrams (mg). More than 500-600 mg per day may increase the risk of negative side effects. Such side effects include insomnia, jitters, nervousness, dehydration, and irritability.  Stopping caffeine intake suddenly can cause headaches, which can be cured by another jolt of caffeine, but may result in a dependence on the compound. But not everyone is affected by caffeine the same way. There is a broad range for an individual’s limit of caffeine due to built-up tolerance as well as genetic differences in ability to break down caffeine.
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