Whole blood (WB) is human blood from a standard blood donation. It is used in the treatment of massive bleeding, in exchange transfusion, and when people donate blood to themselves (autologous transfusion). One unit of whole blood (approximately 450 mL) increases hemoglobin levels by about 10 g/L. Cross matching is typically done before the blood is given. It is given by injection into a vein. Side effects include red blood cell breakdown, high blood potassium, infection, volume overload, lung injury, and allergic reactions such as anaphylaxis. Whole blood is made up of red blood cells, white blood cells, platelets, and blood plasma. It is best within a day of collection; however, it can be stored for up to three weeks if refrigerated (1-6 °C). The blood is typically combined with an anticoagulant and preservative during the collection process. The first transfusion of whole blood was in 1818; however, common use did not begin until the First and Second World Wars. It is on the World Health Organization's List of Essential Medicines. Whole blood is also used to make a number of blood products including red cell concentrates, platelet concentrates, cryoprecipitate, and fresh frozen plasma. Source: Wikipedia (en)