Approach to patients with symptoms of food allergy.

"Allergy" is a term often used by patients to describe symptoms that arise after eating. The term "adverse reaction to food" is preferred unless the event has an immunologic basis. True food allergy, primarily mediated by immunoglobulin (Ig)E antibodies to food proteins, is present in 3% to 4% of US adults. Symptoms range from mild mouth itching ("oral allergy syndrome") to anaphylaxis. The diagnosis is established by history and appropriately performed skin testing or in vitro assays for specific IgE antibodies to the suspected food. Because food-allergic reactions can be fatal, it is important to identify and avoid the causative food. Food-allergic reactions are treated by prompt use of intramuscular epinephrine. Patients may be referred to an allergy/immunology specialist when the diagnosis is uncertain or if avoidance measures are not successful. Investigational therapies may ultimately be preventative or curative.