Food allergy: when and how to perform oral food challenges.

In many situations, the diagnosis of food allergy rests simply upon a history of an acute onset of typical symptoms, such as hives and wheezing, following the isolated ingestion of a suspected food, with confirmatory laboratory studies of positive prick skin tests or Radioallergosorbent tests. However, the diagnosis is more complicated when multiple foods are implicated or when chronic diseases, such as asthma or atopic dermatitis, are evaluated. The diagnosis of food allergy and identification of the particular foods responsible is also more difficult when reactions are not mediated by IgE antibody, as is the case with a number of gastrointestinal food allergies. In these latter circumstances, well-devised elimination diets followed by physician-supervised oral food challenges are critical in the identification and proper treatment of these disorders. Because childhood food allergies to common allergenic foods such as milk, egg, wheat and soy are usually outgrown, oral food challenges are also an integral part of the long-term management of these children.