First, patients with infectious diseases, infectious diseases can obviously spread through blood. If you have an infectious disease, then his blood is definitely useless. If this situation is still bloody, it will not only help people, but also harm people. Therefore, it is generally necessary to test the blood of people with blood before taking blood, and it is necessary to confirm that there is no infectious disease before taking blood.
Second, the sickly person is weak in a short time after blood drawing. If their physical condition is not very good, they often feel dizzy, so they feel dizzy before blood drawing, and may not get out of bed directly after blood drawing. Such people are in poor health, and blood drawing is easy to cause harm to the body, so it is not recommended for people in poor health to donate blood.
Third, when girls come to menstruation, if they want to donate blood, they must avoid the menstrual period. If she is menstruating, she is not suitable for donating blood. During menstruation, the girl is weak and her body is already in a state of blood loss. If blood is drawn at this time, it will make girls' physical condition weaker and their physical resistance lower. Therefore, if girls intend to donate blood, they must avoid menstruation. After replenishing blood, you need to make nutritional supplements, eat more nutritious food and pay attention to rest. Generally, you may feel a little weak on the day of blood drawing, and you can recover after a rest.