Food allergy is an immune system reaction that occurs soon after you eat a food that you are allergic to.

Food allergy is different from a much more common reaction known as food intolerance. While bothersome, food intolerance is a less serious condition that does not involve the immune system.

The most common food allergy signs and symptoms include:

  • Tingling or itching in the mouth
  • Hives, itching or eczema
  • Swelling of the lips, face, tongue and throat or other parts of the body
  • Wheezing, nasal congestion or trouble breathing
  • Abdominal pain, diarrhea, nausea or vomiting
  • Dizziness, lightheadedness or fainting


In some people, a food allergy can trigger a severe allergic reaction called anaphylaxis. This can cause life-threatening signs and symptoms, including:

  • Constriction and tightening of airways
  • A swollen throat or the sensation of a lump in your throat that makes it difficult to breathe
  • Shock with a severe drop in blood pressure
  • Rapid pulse
  • Dizziness, lightheadedness or loss of consciousness

If anaphylaxis is suspected, bring the victim to the hospital immediately. Untreated, anaphylaxis can cause a coma or even death.


Your doctor will perform a physical exam and ask about your symptoms. He may:

  • Ask you to keep a food diary of your eating habits, symptoms and medications to pinpoint the problem.
  • Perform a skin test to determine your reaction to a particular food.
  • Ask you to go on an “elimination diet” in which you temporarily stop eating suspect foods for a week or two and then add the food items back into your diet one at a time.
  • Ask you to take an “oral food challenge” in the clinic. You will be given small but increasing amounts of the suspect food. If you don’t have a reaction during this test, you may be able to include this food in your diet again.



The simplest—and often the best—treatment is to avoid the foods that cause signs and symptoms of food allergy.

As with other types of allergies, avoidance is most often the best medicine. Anyone with a food allergy should be careful when purchasing food at a supermarket or restaurant to make sure there are no traces of the allergen in a food or meal.

For a minor allergic reaction, over-the-counter or prescribed antihistamines may help reduce symptoms.

For a severe allergic reaction, you may need an emergency injection of epinephrine and be brought immediately to the emergency room.

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