If your child consistently gets an upset stomach, hives or swelling after eating a certain food, your child may have a food allergy. When your child is allergic to a particular food (called an allergen), their immune system reacts to protein in the food as if it were harmful. This immune system reaction causes the actual allergy symptoms.
Food allergy reactions can vary from very mild to life-threatening. A severe allergic reaction affecting multiple areas of the body is called anaphylaxis. Anaphylaxis requires immediate emergency medical attention because it can be fatal.