Does green tea have any side effects?

Yes, from caffeine: Green tea has many health benefits, due to its antioxidant effects. There is evidence it can prevent cancer and cardiovascular disease, improve immune function, prevent tooth decay, lower blood sugar and stimulate weight loss. It is safe and generally well tolerated, but it does contain caffeine (though decaffeinated forms are available). Thus, the most common side effects are due to excess caffeine, including insomnia, anxiety, heart palpitations, nausea and vomiting. However, the amount of caffeine in green tea is about 1/4 the amount in coffee, so one will not likely experience such effects unless they drink large quantities. There is also the potential for large amounts of green tea to interact with certain medications- for example, it can reduce the effects of Coumadin (warfarin) (but then again, thousands of substances interact with coumadin!) and lower blood levels of lithium. See http://www.Umm.Edu/altmed/articles/green-tea-000255.Htm for more information.

Oh yes!: Good stuff, but the catechins in green tea that offer lower cancer ; cardiovascular risk may interfere with absorption of drugs via their effects on drug transporters such as p-glycoprotein ; organic anion-transporting polypeptide in gut epithelium. Most recently reported was a negative interaction with antihypertensive effects of nadolol. See http://www.Consultantlive.Com/cardiovascular-disease/.

Potentially: Although green tea is very healthy it does have potential side effects. Green tea is reported to have possible interactions w anticoagulants, stimulants, oral contraceptives, antibiotics ; alcohol. Overdose of green tea (usually extract) may lead to irritability, insomnia, irregular or rapid heart rate, muscle twitching, nausea, vomiting, diarrhea, abdominal cramps, liver damage, trouble.