Hydrochloric acid is harmful to the human body by corroding tissues and causing localized damage to tissues such as the respiratory tract, eyes and skin. Hydrochloric acid is an inorganic strong acid, of which concentrated hydrochloric acid can volatilize acid mist, which will corrode human tissues and irreversibly damage tissues such as the respiratory tract, eyes and skin. If hydrochloric acid is taken accidentally, it can cause localized tissue damage, including erosion of the gastroesophageal mucosa, and can be accompanied by nausea and vomiting. It is necessary to rinse the mouth with plenty of water, or swallow large quantities of raw egg whites or milk, etc., and seek immediate medical attention. If the eyes come into contact with hydrochloric acid, the eyelids should be lifted immediately, and the eyes should be thoroughly rinsed with plenty of water or saline for 15 minutes, and then medical attention should be sought immediately, as the doctor will conduct a thorough examination of the eyes to ascertain the extent of the damage. If the skin comes into contact with hydrochloric acid, you should immediately remove contaminated clothing, rinse with plenty of water, and seek medical attention. The use of hydrochloric acid must pay attention to protection, in the event of accidents, immediate emergency treatment, and as soon as possible to the hospital for follow-up examination and treatment.