The contraindication of green tea is forbidden for those who are allergic to green tea, and the side effect of green tea is affecting the quality of sleep, but there is no side effect when drinking in moderation. Green tea is a common drink in daily life, its nutritional value is relatively high, per 100g of green tea mainly contains protein 34.2g, carbohydrate 50.3g, carotene 5800ug, calcium 0.325g, potassium 1.661g, magnesium 0.196g, phosphorus 0.191g, moderate consumption of green tea is beneficial to human health, can provide nutrients for the body. However, for green tea allergic people need to prohibit the consumption of green tea, so as to avoid the appearance of rashes, skin itching, diarrhea and other allergic reactions. Green tea should not be consumed in excess for a long period of time, because green tea contains the polyphenols, caffeine and other substances, if consumed in large quantities for a long period of time, the above substances may stimulate the central nervous system of the human body, so that the brain is in a state of excitement, and affect the quality of sleep. Therefore, it is recommended to drink green tea in moderation and avoid long-term overdrinking to avoid adverse effects on the body.