Food Allergy

A food allergy is an adverse or abnormal immune reaction to a food or a food additive.

The most common triggers of a food reaction include:

  • Cow's milk
  • Eggs
  • Peanuts
  • Wheat
  • Soy
  • Fish
  • Shellfish
  • Tree nuts, like walnuts and pecans
  • Sesame seeds

You may be more at risk for food allergies if you have a history of eczema or other types of allergies, including hay fever.

Food Allergy Symptoms

Symptoms include:

  • Skin rash, especially hives
  • Swelling (Angioedema) in lips, mouth, tongue throat
  • Stomach cramps or pain
  • Nausea
  • Vomiting
  • Diarrhea
  • Skin itching
  • Cough
  • Wheezing
  • Shortness of breath
  • Nasal congestion
  • Severe drop in blood pressure
  • Gurgling stomach
hives on the skin
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Diagnosing Food Allergies

Your doctor will ask about your symptoms and medical history and perform a physical exam. Food allergies are often diagnosed based on your own observations. It's a good idea to keep a diary of your symptoms and note when your symptoms occur and what you have eaten.

Elimination Diet

The elimination diet should be done under your doctor's care. You will not eat a suspected food. If your symptoms decrease or go away, your doctor may be able to make a diagnosis.

If you eat the food and your symptoms come back, your doctor can confirm the diagnosis. This is most often only done in cases of skin irritation or atopic dermatitis.

Scratch Skin Test

Your doctor places a diluted extract of the food on your forearm or back. Then, your doctor carefully scratches your skin with a small pick or tiny needles. If there is swelling or redness, an allergic reaction may be present.

In rare cases, skin tests can cause a severe allergic reaction. This test should only be used under the supervision of a physician or other trained medical personnel. 


Your doctor may order blood tests (RAST or ELISA) that measure the level of food-specific IgE in the blood. IgE is a type of protein that the body produces when it's exposed to something it's allergic to. The presence of IgE in the blood may indicate an allergy, but this may not be enough to make a diagnosis.

Treating Food Allergies

If you think you've eaten something to which you are allergic, and you have difficulty breathing, call for emergency medical help. Avoid foods and food ingredients that cause you to have an allergic reaction.

Treatments include:

  • Epinephrine — injected immediately in the event of a severe, life-threatening reaction (anaphylaxis)
  • Antihistamine medicine — to decrease swelling and itching
  • Corticosteroid medicine — for more severe swelling and itching

Prevention of Food Allergies

To reduce your chance of having a food allergy reaction:

  • Avoid eating or drinking substances to which you know you are allergic.
  • Read the ingredient label on every food product that you eat.
  • If you go to a restaurant, discuss your allergy with the server. Ask about all ingredients.
  • Learn the other names for all your allergens. This will help you recognize them on an ingredients list.
  • If you have a severe, anaphylactic-type food allergy, ask your doctor if you should carry a dose of epinephrine with you.
  • Consider wearing a medical alert bracelet to inform others of your allergy.
  • Be aware the food may become contaminated by shared utensils, containers and during preparation.



Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.