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Your allergist may recommend allergy tests, such as a skin test or blood test to determine if you have a food allergy. In an allergy skin test for a food, a very small drop of a liquid food extract, one for each food needing to be tested, is placed on the skin. The skin is then lightly pricked. This is safe and generally not painful. Within 15 to 20 minutes, a raised bump with redness around it, similar to a mosquito bite, may appear. This test shows that you are sensitized to the food and probably allergic to that food. A sensitivity to a food can be indicated in a skin prick test or a blood test, but does not always show a true allergy unless there has been a previous reaction to the food.


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Sometimes, an allergy blood test may be used. This typically involves drawing blood from a vein in the arm and the results are not usually available for at least one week.

If done correctly and interpreted by a board-certified allergist, skin tests or blood tests are reliable and can rule in or out food allergy. Some people test "allergic" to a food (by skin or blood testing) and yet have no symptoms when they eat that food. To confirm test results, your allergist may recommend an oral food challenge. This means that you eat or drink small portions of a food in increasing amounts over time to see if an allergic reaction occurs. This is usually done under a physician’s supervision in a doctor’s office or hospital setting.

How do allergists tell which foods make me sick?

Some people know exactly what food causes their allergy. They eat peanuts or a product with peanut in it and immediately break out in a rash. Others need a doctor’s help in finding the cause. Sometimes, the symptoms show up many hours after they have eaten the food.

Your allergy treatment will typically begin with a complete medical history. Your allergist will ask you about:

  • The symptoms you have after eating the food.
  • How long after eating the food these symptoms occurred.
  • How much of the food you had.
  • How often the reaction has occurred.
  • Whether it occurs with other foods.
  • Whether it occurs every time you eat the food.
  • What type of medical treatment, if any, you had.

The medical history will also include questions about your diet, your family's medical history, and your home and living area.

Your allergist asks these questions to find out what is causing your allergy or making your symptoms worse. Allergy to pollen in the air, such as ragweed pollen, can be the cause of the swelling or itching in your mouth and throat if you eat certain foods like melons.

Can special diets help pinpoint the problem?

Your allergist may narrow the search for foods causing allergies by placing you on a special diet. You may be asked to keep a daily food diary. The diary lists all food you eat and medication you take, along with your symptoms for the day.

If only one or two foods seem to cause allergies, you may try avoiding them. In this diet, you do not eat the suspect food at all for one to two weeks. If the allergic symptoms decrease during that period and flare up when you eat the food again, it is very likely the food causing your allergy.

However, which food you should avoid (and for how long) and when you should eat the food again (if ever) should be decided together with your allergist. You should never try to eat even a small quantity of any food your allergist has determined may cause a risk of anaphylaxis.

Your allergist may want to confirm these diet tests with a challenge test. Food allergy testing is a very important step in diagnosing food allergies.

Take back control of your life. See an allergist to find answers with food allergy testing.

This page was reviewed and updated as of 3/18/2019.