Blood transfusion is an important measure for first aid and disease prevention and treatment, but there are certain risks (hazards) associated with blood transfusion, such as allergic reaction, hemolytic reaction, non-hemolytic febrile reaction, and blood-borne infectious diseases such as Hepatitis B, etc. 1. Allergic reaction: when the blood imported carries allergic antibodies or the recipient is allergic to the protein substances in the blood, then allergic symptoms such as respiratory difficulties and urticaria may occur during the transfusion process, and anaphylactic shock may occur in serious cases, or even death. 2. Hemolytic reaction: due to the recipient’s autoimmune reasons, the input red blood cells are abnormally destroyed in the body, thus triggering the adverse reaction of blood transfusion, which is clinically manifested as chills, fever, shortness of breath, drop in blood pressure and other symptoms. 3. Non-hemolytic febrile reaction: If there is pyrogen in the blood products, the recipient may produce anti-platelet or white blood cell antibodies, which may cause immune reaction and symptoms such as fever, chills and vomiting. 4. Blood-borne diseases: the recipient may be infected with some viruses due to blood transfusion, thus inducing the occurrence of diseases, such as hepatitis viruses HCV, HIV, HBV, syphilis and so on. Blood transfusion plays an important role in saving the patient’s life, so if you encounter this kind of situation, you should weigh the pros and cons with the assistance of your doctor, and you should not blindly refuse it because of the risks involved, which may lead to serious consequences.