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.
The allergic reaction may be mild. In rare cases it can cause a severe reaction called anaphylaxis. Symptoms of food allergy include
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