Approach to determining when to test for IgE-mediated food allergies based upon clinical history

This algorithm summarizes our approach to determining whether testing for IgE-mediated food allergies is warranted based upon the clinical history. It is intended for use in conjunction with other UpToDate content. Several factors determine whether a history is consistent with an IgE-mediated reaction, including the signs and symptoms of the reaction (common findings include urticaria, nausea/vomiting, wheezing), timing in relation to food ingestion (usually within minutes), and the food trigger suspected (eg, a common allergen such as peanut). Other features of the reaction to consider include contributing factors (eg, exercise) and response to treatment (eg, improved after treatment with an antihistamine or epinephrine). If all factors of the history are consistent with an IgE-mediated reaction, the pretest probability is very high. If some are present, the pretest probability is intermediate. If most to all of the factors are absent, then an IgE-mediated reaction is unlikely (low pretest probability), and testing is usually not performed. Refer to UpToDate topic on IgE-mediated food allergies for additional details regarding presentation and diagnosis.