Food allergy is an abnormal response to a food triggered by your body's immune system.

In adults, the foods that most often trigger allergic reactions include fish, shellfish, peanuts, and tree nuts, such as walnuts. Problem foods for children can include eggs, milk, peanuts, tree nuts, soy, and wheat.

Symptoms of food allergy include

• Itching or swelling in your mouth
• Vomiting, diarrhea, or abdominal cramps and pain
• Hives or eczema
• Tightening of the throat and trouble breathing
• Drop in blood pressure

Your health care provider may use a detailed history, elimination diet, and skin and blood tests to diagnose a food allergy.

When you have food allergies, you must be prepared to treat an accidental exposure. Wear a medical alert bracelet or necklace, and carry an auto-injector device containing epinephrine (adrenaline).

You can only prevent the symptoms of food allergy by avoiding the food. After you and your health care provider have identified the foods to which you are sensitive, you must remove them from your diet.

NIH: National Institute of Allergy and Infectious Diseases