Preservatives usually include food preservatives and chemical preservatives. If consumed in excess, food preservatives may affect the balance of metabolism in the body and may even damage the liver and kidneys. If contacted or ingested, chemical preservatives may cause allergy, poisoning and other symptoms to the human body. 1. Food preservatives: Food preservatives include a variety of, such as sorbic acid and potassium sorbate in food preservatives. As internationally recognized as relatively safe preservatives, they usually do not affect the intestinal flora of the human body and can be degraded by the digestive tract. However, large intake can also affect the balance of metabolism in the body, and even damage the liver and kidneys. 2. Chemical preservatives: usually have a strong irritant and corrosive. For example, common formalin preservatives, mainly used for soaking animal specimens. If the skin comes into contact with formalin, it may cause an allergic reaction. If accidentally ingested, it will lead to acidosis of the organism, and symptoms such as gastrointestinal erosion and respiratory failure may occur. Therefore, if a patient develops symptoms of physical discomfort due to preservatives, he or she should go to the hospital in a timely manner to avoid delaying the condition.