Factor VIII, an essential blood coagulation protein,[11] is used as a medication to treat and prevent bleeding in people with hemophilia A and other causes of low factor VIII.[12] Certain preparations may also be used in those with von Willebrand's disease. It is given by slow injection into a vein.[12]
Side effects include skin flushing, shortness of breath, fever, and red blood cell breakdown.[12] Allergic reactions including anaphylaxis may occur. It is unclear if use during pregnancy is safe for the fetus.[13] A purified factor VIII concentrate is made from human blood plasma.[14]