Patients with high blood pressure cannot donate blood because there are national requirements for the health of blood donors, one of which is that the donor’s blood pressure should not exceed 140/90mmHg. If the blood pressure is not well controlled and is often above 140/90mmHg, you cannot donate blood. Even if your blood pressure is under control, you cannot donate blood because blood donation may cause mental tension and other conditions that may lead to fluctuations in blood pressure and induce other cardiovascular and cerebrovascular accidents. Blood donation is only allowed if there are no other abnormalities in the body, such as normal liver function, no high blood pressure, blood sugar or lipid levels, no infectious diseases, etc. Nowadays, there is a saying that people with hypertension can lower their blood pressure by donating blood. This saying has no scientific basis, because high blood pressure is not directly related to blood volume or blood viscosity. High blood pressure is related to many factors, such as smoking, drinking, staying up late, not exercising and other bad habits, as well as often in a state of tension, and genetic factors, etc. For patients with high blood pressure, they should still take antihypertensive drugs regularly and actively control their blood pressure smoothly. At the same time, in life should also pay attention to low salt and low fat diet, to stop smoking and alcohol, do not stay up late, should also exercise more exercise, and actively control the weight, so as to help the blood pressure control. Therefore, for patients with high blood pressure, it is best not to donate blood. It is better to actively and steadily control blood pressure.