According to WebMD, green tea is bad for the health if the body consumes more than five cups per day, as it can cause side effects due to the high amount of caffeine in the tea. Side effects include headaches, sleeping problems, anxiety, nervousness, irritability, heartburn, dizziness and irregular heartbeat.
Consumption of too much green tea can also reduce the intake of iron from food, according to WebMD. High doses of green tea are toxic to the body and can possibly be fatal, due to high doses of caffeine.
Green tea is also bad for pregnant and breast-feeding woman, as drinking more than two cups of green tea daily increases the probability of miscarriage and other negative pregnancy effects. Caffeine can also flow into breast milk, which affects the diet and nutrition of the infant.
Consumers with anxiety disorders should not drink too much green tea, as it worsens anxiety, according to WebMD. People with diabetes should also not drink too much green tea, as the caffeine in green tea can affect blood sugar levels and control. Consumers with high blood pressures should be careful of drinking too much green tea, because the caffeine in green tea can increase blood pressure. The caffeine in green tea can also worsen the conditions of diarrhea.