The feeling that your heart is racing or skipping -- known as heart palpitations -- is a common side effect of excessive caffeine consumption. Although the caffeine content of green tea is relatively low, you may still experience an increase in heart rate if you drink too many cups.
An 8-ounce cup of green tea contains roughly 15 milligrams of caffeine, according to the University of Utah. Green-tea energy drinks may have a higher caffeine content.
Benefits and Recommendations
Green tea has several beneficial nutrients, including cancer-fighting antioxidants. If you find yourself sensitive to small quantities of caffeine, you won't miss out on any of the health benefits of green tea by opting for caffeine-free varieties. Otherwise, the University of Maryland Medical Center recommends that you limit yourself to 2 to 3 cups of caffeinated tea per day.