Dizziness and nausea when drinking black tea is because tea contains many substances, including caffeine, theophylline and other substances acting on the human body, which can easily induce lower blood sugar, lower blood pressure, dizziness, nausea, vomiting, numbness in the hands and feet, sweaty palms, which can be relieved by resting and eating some sweet food. When drinking black tea as well as green tea must drink light tea, do not drink strong tea, otherwise it will strongly stimulate the central nervous system, so that the body secretes a lot of adrenaline, inducing the appearance of hypoglycemia, insomnia, anxiety, irritability, etc., in the clinical must be noted. Try not to drink tea before going to bed, otherwise it will aggravate the symptoms of insomnia and cause poor sleep quality.