Many of the negative side effects of consuming green tea are associated with its caffeine content, including headache, nervousness, trouble falling asleep, vomiting and diarrhea, according to WebMD. Other negative side effects include irregular heartbeat, irritability, tremors, convulsion and general confusion.
Some people may experience constipation because of green tea. Other people might experience severe liver problems if they consume green tea, notes WebMD. Women who are pregnant can more than likely safely consume about 200 milligrams of green tea a day, which is equal to 2 cups. Consuming more than this amount of green tea is linked to miscarriages and negative birth effects. Green tea can make people with irritable bowel syndrome experience problems, while people with glaucoma can experience increased pressure in the eyes.