Strong tea contains high levels of fluorine, tannic acid, caffeine, theophylline and other ingredients, a large amount or long-term drinking of strong tea will excite the central nervous system, which may cause insomnia. In addition, it may also have adverse effects on the gastrointestinal tract, heart, kidneys, etc.: 1, central nervous system: strong tea in the caffeine, theophylline and other components, can make the central nervous system excitability increased, the brain overexcited, may cause insomnia; 2, gastrointestinal tract: strong tea in the caffeine, theophylline and other components, can promote the secretion of gastric juice, gastrointestinal peristalsis accelerated, long-term drinking strong tea will cause stimulation of the gastric mucosa, the Causes nausea, vomiting, diarrhea and other uncomfortable symptoms, but also increase the risk of gastritis, gastric ulcer, duodenal ulcer and other diseases; 3, heart: drinking strong tea can excite the sympathetic nerve, causing an increase in heart rate, hypertension, heart disease patients drinking large amounts of strong tea may aggravate the condition, or even cause other discomfort; 4, kidneys: strong tea contains fluorine, and fluorine is mainly metabolized through the kidneys, drinking strong tea intake of large amounts of fluorine, will increase the kidney burden. In addition, tea is rich in tannic acid, long-term drinking of strong tea may lead to kidney stones; 5, other: during drug treatment, drinking a lot of strong tea can reduce the effectiveness of the drug to a certain extent, the ingredients in strong tea can inhibit the effect of drugs or make the drug decomposition, for the treatment of disease is not beneficial. In addition, drinking strong tea may affect the body’s absorption of calcium, accelerating the excretion of calcium, calcium deficiency in the body, may lead to osteoporosis, and even fractures. And strong tea contains a lot of tannic acid, which can affect the absorption of iron, leading to anemia and other problems. It is recommended to drink less or not to drink strong tea, so as not to have adverse effects on the body, can drink light tea in moderation.