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constipation. Green tea extracts have been reported to cause liver problems.
Too much green tea, such as more than five cups per day, can cause side effects because of the caffeine. These side effects can range from mild to serious and include headache, nervousness, sleep problems, vomiting, diarrhea, irritability, irregular heartbeat, tremor, heartburn, dizziness, ringing in the ears, convulsions, and confusion. Green tea seems to reduce the absorption of iron from food.
If you are pregnant or breastfeeding, green tea in small amounts is probably not harmful. Do not drink more than 2 cups a day of green tea. This amount of tea provides about 200 mg of caffeine. Consuming more than this amount has been linked to an increased risk of miscarriage and other negative effects.
Caffeine is probably safe in children in amounts commonly found in foods.
Avoid consuming large amounts of green tea if:
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.