Tea expired even if not opened is not recommended to drink again, the shelf life is the normal state, environment, temperature, storage methods, to ensure food safety and health period. Food beyond this period is prone to deterioration, mold, can not ensure food safety, but also may produce substances harmful to humans such as aflatoxin, ochratoxin A, etc.. Sometimes the naked eye can not see the change, but the nature may have changed, at this time drinking may appear uncomfortable, but also not beneficial to the human body. 1, induce disease: easy to cause abdominal pain, diarrhea, vomiting and other digestive discomfort, if the tea produced toxins into the body may also cause food poisoning, dizziness, fever, weakness, body aches and other symptoms, may also affect the human respiratory system, the nervous system 2, the reduction of nutritional value: expired tea may have deteriorated, its nutrients such as minerals, phosphorus, potassium, zinc, etc. will gradually lose, far less than the nutrition of fresh tea water; 3, the taste becomes worse: the taste of expired tea will become worse, compared with fresh tea is not enough fragrant, rich, may also produce odor, affecting the taste of drinking, while the taste of fresh tea is usually more distinct, sweet, layered The taste of fresh tea is usually more distinct, sweet and layered.