1. Drinking black tea will increase the body temperature of patients with fever, which may reduce the curative effect if they are taking medicine;
2. People with neurasthenia drinking black tea will stimulate the nerve center of the brain and aggravate the symptoms of insomnia;
3. Anemia patients who drink black tea may have tannic acid combined with iron to aggravate anemia and form insoluble substances at the same time;
4. Drinking black tea in patients with ulcers will stimulate gastric acid secretion and aggravate the condition;
People who are malnourished drink black tea, which will accelerate the decomposition of body fat and further aggravate the deficiency of body nutrition.