Intravenous immunoglobulins are stable pooled human IgG preparations for therapeutic use. Intravenous immunoglobulins are used for replacement therapy for patients with primary or secondary antibody immunodeficiency, and they are also beneficial in the prevention and treatment of certain viral infections, such as cytomegalovirus pneumonia and Varicella-Zoster; they may also have a synergistic effect with antibiotics in some bacterial diseases. Intravenous immunoglobulins have also been used successfully in the treatment of idiopathic thrombocytopenic purpura, Kawasaki disease and other autoimmune diseases such as Graves ophthalmopathy. Disadvantages of intravenous immunoglobulins include some frequent (10%) but usually not serious side effects and high cost; rarely has transmission of viral infections been reported.