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How is a double-blind food challenge done to diagnose food allergies?

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The double-blind food challenge has become the gold standard of allergy testing. Various foods, some of which are suspected of inducing an allergic reaction, are each placed in individual opaque capsules. The patient is asked to swallow a capsule and is then watched to see if a reaction occurs. This process is repeated until all the capsules have been swallowed. In a true double-blind test, the doctor is also "blinded" (the capsules having been made up by some other medical person) so that neither the patient nor the doctor knows which capsule contains the allergen.

The advantage of such a challenge is that if the patient has a reaction only to suspected foods and not to other foods tested, it confirms the diagnosis. Someone with a history of severe reactions, however, cannot be tested this way. In addition, this testing is expensive because it takes a lot of time to perform and multiple food allergies are difficult to evaluate with this procedure.

Consequently, double-blind food challenges are done infrequently. This type of testing is most commonly used when the doctor believes that the reaction a person is describing is not due to a specific food and the doctor wishes to obtain evidence to support this judgment so that additional efforts may be directed at finding the real cause of the reaction.

From: Food Allergy and Food Intolerance WebMD Medical Reference

SOURCES:

The National Institute of Allergy and Infectious Diseases: "Fact Sheet: Food Allergy and Intolerances."  UpToDate. American Academy of Allergy Asthma & Immunology.

Reviewed by Brunilda Nazario on October 29, 2018

SOURCES:

The National Institute of Allergy and Infectious Diseases: "Fact Sheet: Food Allergy and Intolerances."  UpToDate. American Academy of Allergy Asthma & Immunology.

Reviewed by Brunilda Nazario on October 29, 2018

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