Hizentra is used to strengthen the body's natural defenses against infection in people with a condition that weakens the immune system. Immunoglobulins contain natural substances called antibodies (a type called IgG) that come from healthy human blood. These antibodies help protect your body against infection and help you fight infection if you get sick. Some immunoglobulin products may also be used to treat a certain nerve disorder (chronic polyneuritis - CIDP).