Idiopathic thrombocytopenic purpura (ITP) is an immune disorder in which the body attacks the cells responsible for blood clotting (platelets), resulting in bleeding. The cause of ITP is not known (idiopathic).

People with this disorder may have bruises or black-and-blue marks (purpura) on the skin. Internal bleeding is a more serious complication that can occur.

Some cases of ITP may go away on their own and do not require treatment. In other cases, treatment may be needed to control bleeding. Some medicines can help the body make more platelets. Steroid medicine (such as prednisone) also may be needed to suppress the immune system. An intravenous (IV) infusion of a substance made from human blood plasma (immunoglobulin) may be given. Sometimes it is necessary to have platelet transfusions. In rare cases, the spleen may need to be removed.