The diagnosis of a food allergy requires consideration of the details of an individual's history, knowledge about the epidemiology of different food allergies, and specific test results. When these elements do not clearly confirm or refute an allergy, the clinician, typically an allergy specialist or sometimes a gastroenterologist, may perform a clinician-supervised oral food challenge (OFC) [1-6]. OFCs may also be used to determine if a food allergy has resolved. In addition, they can be undertaken to define other adverse reactions to foods, such as intolerance.
OFCs generally consist of a gradual feeding of the test food under close observation. The test usually results in a definitive conclusion about whether the food was tolerated.
An OFC is preceded by a period of dietary elimination, performed either therapeutically (because the food was already suspected or known to have caused a reaction) or for diagnostic reasons (to determine if elimination of the suspect food resulted in amelioration of symptoms).
This topic review will present the role of diagnostic elimination diets, the selection of patients for OFCs, different types of OFCs, and a general approach to performing an OFC. Other related food allergy topics are covered separately. (See "Diagnostic evaluation of food allergy" and "Management of food allergy: Avoidance" and "History and physical examination in the patient with possible food allergy" and "The natural history of childhood food allergy".)
Elimination diets are performed prior to an oral food challenge. Elimination diets are used diagnostically to determine if symptoms, usually chronic in nature, resolve after the suspected food(s) is removed from the diet. Elimination diets are discussed in greater detail in another review, and avoidance of a food allergen once the allergy is diagnosed is presented separately. (See "Diagnostic evaluation of food allergy" and "Management of food allergy: Avoidance".)