An elimination diet is used to identify and remove foods and ingredients that provoke allergic reactions in a patient. During this process, patients eliminate all suspected foods or ingredients from their diets for a period of time. Patients who eventually find themselves symptom-free then gradually reintroduce suspected foods back into their diet, one by one. When a reintroduced food sparks a reaction, an allergy diagnosis is usually made. An elimination diet can also be used to detect some food sensitivities or intolerances.

A food challenge test is a variation on the elimination diet. This test takes place in a controlled environment in a single session. During the test, a physician exposes the patient to suspected foods or ingredients in hopes of actually provoking an allergic reaction.

Elimination diets and food challenge tests can accurately reveal the nature of a patient’s food allergy. However, the tests can be time-consuming, and establishing a connection between an allergen and a reaction can be difficult. In addition, they may be too dangerous for those whose food allergies provoke anaphylactic shock, a life-threatening, whole-body allergic reaction. It is very important that an elimination diet be performed only under a physician’s supervision.

An elimination diet usually lasts for a period of weeks. Over this period it is important that a patient conscientiously follow the diet without cheating. Straying from the diet even a little can ruin the diagnostic capability of the test.