Oral Challenge Test

An oral challenge test can be a very helpful allergy testing method when dealing with food allergies. With food allergies, your medical history, skin tests, and blood tests may not provide the allergist with enough information for diagnosis. In those cases an oral challenge test may be needed. An oral challenge test done by feeding you the food being tested for in increasing amounts, waiting 10-30 minutes between each serving, until a full serving of the food has been eaten or you have had an allergic reaction.

Why would I need an oral challenge test?

Oral challenge tests are beneficial for ruling out food, food additive, and medication allergies but are most commonly used for food allergies. Oral challenge tests are typically done after a skin test has been negative for a suspected trigger food.

This type of test should only be done in a medical setting by a trained professional, such as an allergist. Doing an oral challenge test at home can be unsafe and inaccurate because many foods may be contaminated with pollen, pesticides, or other chemicals.

What are the different types of oral challenge tests?

There are three types of oral challenge tests:

  • Open food challenge. This is the most common type of oral challenge test. During this test the possible trigger food (the food being tested for) is not hidden so both you and the allergist know what food you are being tested for. This test can be inaccurate because you may “think” you are having a reaction to a food, especially if you go into the test “thinking” you are allergic.
    • Following the test you may need to be observed in the allergist’s office for several hours to make sure there is no delayed allergic reaction.
  • Single-blind oral food challenge. In this test the allergist would hide the suspected trigger food so you wouldn’t know what food you were being tested for. This prevents you from “thinking” you are having symptoms, especially with foods you “think” you are allergic to.
  • Double-blind oral food challenge. During this test the food is hidden from both you and the allergist. This is the best type of oral challenge test because it eliminates bias from you and the allergist.

Two weeks prior to testing the allergist may request that you follow an elimination diet. When the food is disguised it is hidden in capsules to hide the taste and smell of the food. In all tests, the suspected trigger food is given in increasing amounts until a normal serving is eaten.

What happens if my oral challenge test shows I have an allergy?

A result has a positive result if you have any symptoms after eating the possible trigger food, such as:

  • Itchy skin, rash, or hives
  • Itchy lips, mouth, or throat
  • Sneezing, coughing or wheezing
  • Runny nose
  • Nausea, vomiting, or diarrhea
  • Lightheadedness or dizziness
  • And sleepiness to name a few

The most common positive reactions to oral challenge tests are respiratory (e.g. coughing and wheezing) and gastrointestinal (e.g. nausea, vomiting, or diarrhea) symptoms. Positive findings may result in removing the food from your diet.

Is there any reason I can’t have an oral challenge test?

You should not have an oral challenge test if you:

  • Have a history of a severe reaction or anaphylactic reaction to a possible trigger food.
  • Are already having allergic symptoms on testing day.
  • Have an unstable health condition.
  • Have poorly controlled asthma, eczema, psoriasis, or are pregnant.
  • Are unable to temporarily stop the medications requested by your allergist, such as heart medications (e.g. beta blockers) and anti-histamines (e.g. Benadryl).
  • Are unable to eat or cooperate with the testing, as is the case with infants and some children.

 

References

Disclaimer: The information contained in this site is for educational purposes only, and should not be used as a substitute for a licensed physician. Please see your physician for diagnosis and treatment of any concerning symptoms or medical condition. Click here to read the full disclaimer.
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