Immune globulin is sometimes used to treat idiopathic thrombocytopenic purpura (ITP), an immune disorder in which the body attacks the cells responsible for blood clotting (platelets), resulting in mild to severe 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. Steroid medication (such as prednisone) also may be needed to suppress the immune system. In rare cases, the spleen may need to be removed.