A positive skin prick test and/or a positive food blood test are indicative of allergic sensitization, but these findings alone may or may not be clinically relevant. Food allergy experts agree that verification of clinical reactivity oftentimes require a well-designed oral food challenge. In addition to verifying food allergy, challenge testing prevents unnecessary dietary avoidance and enhances compliance with the elimination diet.
Prior to initiating an oral food challenge, suspected foods are eliminated from the diet for 2 to 8 weeks depending upon the type of food allergic reaction being examined. After documenting significant improvement on dietary elimination, the challenge test is carried out while the patient is on no medications. The food challenge test is designed and performed under medical supervision to document the dose that provoked the reaction and to administer symptomatic treatment, which may require management of anaphylaxis. Food challenge begins with a low dose, which is then gradually increased, while monitoring for any symptoms, until a cumulative dose at least equal to the usually eaten quantity is reached. Due to the risk of a severe reaction, intentional challenge should be avoided in patients who have recently experienced a life-threatening reaction to a particular food. Food challenge can be performed to any suspected foods, but the most common foods tested are peanut, milk, soy, wheat and eggs.
