Although blood donation is a spontaneous activity, there are certain requirements. Before donating blood, a detailed examination will be conducted and the health condition of the donor and the amount of blood donated in a single visit will be evaluated, and in general, moderate blood donation for healthy people will have minimal impact on the body and no significant harm, and will also help to enhance the hematopoietic function. Therefore, a single visit to a regular medical institution for blood donation is generally not risky, let alone the six major hazards, but does not exclude transient discomfort after blood sampling. 1. dizziness: a decrease in peripheral blood volume and a corresponding decrease in blood supply to the brain can cause insufficient blood supply to the brain, resulting in hypoxic dizziness; 2. increased risk of infection: blood donation procedures that are not properly sterilized can cause blood infection, making it easy to infected with AIDS, hepatitis B and other blood-borne diseases. If a large amount of blood is donated over a long period of time or due to unexpected circumstances, it can also cause a corresponding burden on the body and even pathological changes, but generally there are not as many as six. Long-term, large amounts of blood donation may cause the following hazards to the human body: 1. Vascular brittleness: frequent blood donation can cause vascular scarring, reduce vascular elasticity and ductility, and easily cause vascular rupture; 2. Addiction: blood donation can enhance the body’s hematopoietic Blood donation can enhance the body’s hematopoietic capacity. Frequent blood donation can cause the body’s hematopoietic capacity to be hyperactive, increase peripheral blood volume, and feel blood spurting, wanting to relieve vascular pressure by donating blood; 3, anemia: as we age and our physical condition declines, the compensatory effect of organs on blood loss gradually decreases, and the hematopoietic capacity gradually decreases. Some men may also experience a decrease in sexual function. 4. Obesity: Most continuous blood donors respond by gaining weight after long-term blood donation, which may be a compensatory effect of the body for blood loss. In addition, the average person donates 200-400 ml of blood in a single session. If, due to certain special moments, the donor needs to donate a large amount of blood, there is a risk of organ damage, such as the occurrence of hemorrhagic shock, ischemic heart disease, etc. At this time, the blood needs to be stopped, and at the same time, timely transfusion treatment is required.