(1) Transfusion reaction—immediate or delayed, seen in 1-4% of transfusions; IgA-deficient pts at particular risk for severe reaction; (2) infection—bacterial (rare); hepatitis C, 1 in 1,800,000 transfusions; HIV transmission, 1 in 2,300,000; (3) circulatory overload; (4) iron overload—each unit contains 200- to 250-mg iron; hemochromatosis may develop after 100 U of RBCs (less in children), in absence of blood loss; iron chelation therapy with deferoxamine indicated; (5) graft-versus-host disease; (6) alloimmunization (Table 8-1).