The fastest way to replenish blood in patients with severe anemia is by transfusion of red blood cells. Severe anemia is defined as hemoglobin concentration less than 60g/L. The treatment of severe anemia can be divided into symptomatic treatment and causative treatment. 1. Symptomatic treatment: mainly transfusion of red blood cells and correction of anemia; if combined with acute blood loss, plasma transfusion is also needed to restore blood volume; if combined with bleeding, hemostatic treatment is needed. 2. Causative treatment: for example, iron deficiency anemia should be treated with iron supplementation and the causes of iron deficiency should be removed as far as possible; megaloblastic anemia should be treated with the treatment of the original disease and supplementation of folic acid or vitamin B12; hemolytic anemia should be treated by actively searching for the causes of the disease, and most of them are treated with glucocorticoid or splenectomy. Aplastic anemia should be treated with immunoglobulin, cyclosporine, androgens, and bone marrow transplantation if necessary; all types of secondary anemia should be treated for the primary disease. If anemia occurs, you should go to the hospital in time and be treated under the guidance of a specialist.