Food Challenge Testing and Diagnosing Allergies

The Tool of Last Resort in Many Cases of a Suspected Food Allergy

Sep 14, 2009

In some cases the health care professional will need to conduct an oral challenge, an elimination test or a double-blind food challenge to complete an allergy diagnosis.

Food challenges are often used when other testing leaves a doubtful diagnosis or if the physician suspects that the patient is outgrowing the allergy.

A Food Elimination Allergy Test

There are cases where the physician may instruct the patient to avoid certain foods or substances to see if the allergy symptoms lessen. If the reactions in these cases are not severe, the medical professional may suggest using some of the foods or substances to see if the symptoms reappear.

If this test is carried out by eliminating certain foods for a couple of weeks or more, nutrition will need to be monitored carefully. It is important for the patient to maintain a balanced diet.

Any type of food or substance elimination testing should not be conducted at home without the approval and instructions of a health care professional.

A Food Oral Challenge Allergy Test

When a skin test fails to diagnose a food or drug allergy, the physician may use an oral challenge to get more information. An oral challenge has the risk of causing anaphylaxis, so it is carried out in a controlled setting, such as the physician’s office or a hospital.

The patient is given small doses of various suspected allergens, then monitored closely for the signs of an allergic reaction. In the controlled setting, emergency aid can be given immediately if the need arises.

A Double-blind Food Challenge Allergy Test

This test is done without the patient or doctor knowing which capsules contain which substances. This way there is no chance of the patient having an emotional reaction to a substance that she thinks she is allergic to, thus avoiding a stress-related reaction.

Even though neither the patient nor the health care professional knows which capsules contain which substances, they are labeled and recorded for analysis after the test.

When the double-blind food challenge is done using a placebo, it is called the Double-blind Placebo-controlled Food Challenge (DBPCFC). If the patient has the same symptoms with the placebo as with the food, she is probably experiencing anxiety about the testing. This form of food challenge is considered the gold standard in food testing and the last resort – it is expensive.

This type of testing is also carried out in a controlled setting to ensure that emergency help and materials are on hand in case of a severe allergic reaction.

Food challenge testing is usually used when other forms of testing and analysis leave doubts about the diagnosis. However, these types of tests have a high percentage of accuracy and rarely result in a false negative.

Disclaimer: This article is intended for information purposes only. It is not a substitute for medical attention and supervision.

Ehrlich, Paul M. Teen’s Guides: Living with Allergies. New York: Checkmark Books, 2009.

Barber, Marianne S. The Parent’s Guide to Food Allergies: Clear and Complete Advice from the Experts on Raising Your Food-allergic Child. New York: Henry Holt and Company, 2001.

Hospital for Sick Children: The Complete Kid’s Allergy and Asthma Guide: The Parent’s Handbook for Children of All Ages. Ed. Dr. Milton Gold. Toronto, Canada: Robert Rose Inc., 2003.

Website: American Academy of Allergy, Asthma and Immunology, updated March, 2005. Visited September 11, 2009.

The copyright of the article Food Challenge Testing and Diagnosing Allergies in Food Allergies is owned by Stella Walsh. Permission to republish Food Challenge Testing and Diagnosing Allergies in print or online must be granted by the author in writing.