Food allergy. Part 2: diagnosis and management.

Patients with food-induced allergic disorders may be first seen with a variety of symptoms affecting the skin, respiratory tract, gastrointestinal tract, and/or cardiovascular system. The skin and respiratory tract are most often affected by IgE-mediated food-induced allergic reactions, whereas isolated gastrointestinal disorders are most often caused by non-IgE-mediated reactions. When evaluating possible food-induced allergic disorders, it is often useful to categorize disorders into IgE- and non-IgE-mediated syndromes. The initial history and physical examination are essentially identical for IgE- and non-IgE-mediated disorders, but the subsequent evaluation differs substantially. Proper diagnoses often require screening tests for evidence of food-specific IgE and proof of reactivity through elimination diets and oral food challenges. Once properly diagnosed, strict avoidance of the implicated food or foods is the only proven form of treatment. Clinical tolerance to food allergens will develop in many patients over time, and therefore follow-up food challenges are often indicated. However, a number of novel immunomodulatory strategies are in the developmental stage and should provide more definitive treatment for some of these food-induced allergic disorders in the next several years.