Food Allergy Diagnosis and Treatment

The oral food challenge involves eating a serving of the allergic food in a slow, graded fashion under medical supervision. The food challenge procedure is the most accurate test to determine whether a food needs to be avoided or will no longer need to be avoided.

The food challenge is undertaken when you or your child is in generally good health and can discontinue antihistamine for a brief period (usually three days) before the test.

During the food challenge, you or your child will be given very small amounts of the specific food being tested. If tolerated, increasing amounts of the challenge food will be given with close observation at each stage.

You or your child will be observed for symptoms such as itching, rash, abdominal pain or difficulty breathing. If any symptoms develop, treatment will begin immediately. In most cases, this will involve the use of diphenhydramine and/or epinephrine to prevent any allergic reactions from getting worse. In studies of food challenges, many children develop mild symptoms during a food challenge that require these treatments. Very rarely, other treatments are needed for more serious reactions.

In some cases, your doctor may decide to place an IV in you or your child’s arm before the challenge starts. This would be used to give medicine if needed.

Sometimes, the food challenge is performed by masking the food to hide the taste, and using food that looks/tastes the same but does not contain the food being tested. This is called a placebo. These procedures reduce the possibility that we would misjudge a reaction to the food that could occur from fear or distaste of the new food.

The discomforts associated with the food challenge are generally no more than those encountered when eating the food. Symptoms usually are short-lived (less than two hours). Symptoms may include an itchy skin rash, nausea, abdominal discomfort, vomiting, diarrhea, stuffy “runny” nose, sneezing or wheezing.

Major risks include severe breathing difficulties and, in rare cases, a drop in blood pressure. While a severe outcome such as death is theoretically possible, this has not occurred from medically supervised oral food challenges. The risk of a reaction is reduced by starting the challenge with very small amounts of food, administering the food over a prolonged time period, stopping the challenge at the first sign of a reaction and by not giving any food suspected to cause a major reaction.

Medications, personnel and equipment will be immediately available to treat allergic reactions should they occur.

• Stop all antihistamines three days before the challenge (e.g. cetirizine, loratidine, fexofenadine, diphenhydramine).
• Continue all asthma medications even on the day of the challenge.
• Contact your doctor if you or your child has been on oral steroids (e.g. prednisone, prednisolone, etc.) in the two weeks prior to the challenge or has had to use a rescue inhaler (e.g. albuterol, levalbuterol) in the two days prior to the challenge.
• Pack a bag with games, toys and DVDs to bring to the oral food challenge since you'll at the procedure for several hours.
• Pack food that will be used for the challenge as instructed by your doctor.
• Call before leaving for the challenge if you or your child develop a fever, nausea, vomiting, wheezing or other illness.
• No food two hours prior to the challenge (clear liquids are okay).
• Bring your epinephrine autoinjector to the procedure with you.