THE word "allergy" is coined from two Greek words meaning altered reactivity. A food allergy occurs when the immune system responds defensively to a specific food protein that is not harmful to the body. A severe food allergic reaction known as anaphylaxis usually occurs within minutes of eating the offending food and symptoms. It may include a tingling sensation of the mouth, swelling of the tongue and throat, hives (urticaria), skin rashes, vomiting, rhinitis, abdominal cramps, difficul.