What is an oral food challenge
An oral food challenge (OFC), is where your child is slowly fed a food, in gradually increasing amounts, under medical supervision. It is used to accurately diagnose or rule out a true food allergy.
What are the reasons to perform an OFC?
OFCs are usually done when the medical history and allergy tests are inconclusive. The OFC is a definitive test because it will show whether the food ingested produces no symptoms or causes an allergic reaction.
What do I need to do in preparation to have an OFC?
Your child needs to be well on the day of the test. If your child is unwell it can cause them to react more severely on the day. If your child is sick on the day of the OFC, it should be postponed. You should also carry your child’s usual medications and emergency medications with you so you have them for the trip to the clinic and back.
Do I have to stop any medications before having an OFC?
Antihistamines (Claratyne, Zyrtec, Telfast, Aerius) have to be stopped before the OFC. This is because they might mask mild early symptoms. Ask the clinic how long your child needs to be off their antihistamine before their OFC.
NEVER avoid using a needed emergency treatment such as an EpiPen (adrenaline), antihistamines or inhaled asthma rescue medications just because you have an OFC scheduled. Treat the problem and postpone the test.
Who provides the food?
Please talk to the clinic about this. You may be asked to bring in specific food items on the day of the challenge. This can depend on your child’s food preferences. For example infants, younger children or picky eaters, may need to have several food options ready to minimise the possibility of food refusal on the day of the food challenge.
We encourage you bring your child’s favourite serving dishes and utensils. Our clinic also highly recommends bringing in distractions such as toys, books, or homework.
What happens on the day of the test?
Your child does not need to fast on the day. We do recommend only a small meal, so they are not full and then may be reluctant to eat the food offered to them during the oral food challenge.
A physical examination and vital signs are done before starting the OFC. The OFC starts with a small serving of the food and after a period of time, usually 20 minutes, if no symptoms are present, a slightly larger amount is given to your child to eat.
If symptoms occur and our team feel that your child is reacting, the feeding is stopped. Medications will be given to your child as needed. If your child is not reacting, they continue to be fed until a meal-sized portion is eaten.
What is the usual treatment in case of an allergic reaction during an OFC?
In most cases the symptoms are usually mild because the testing is done gradually and feeding is stopped at the onset of symptoms. Most often, antihistamines are given for these mild symptoms. If there are more severe symptoms (anaphylaxis), treatments can include adrenaline given as an injection in the thigh and other medications. IF it is a severe reaction other emergency steps like calling an ambulance will be taken.
How long do I have to stay after the feeding is over?
If there were no symptoms during an OFC, usually patients are discharged from the clinic within 2 hours of completing the challenge. In case of allergic symptoms your child will be watched for at least 2 to 4 hours from the time symptoms go away or improve. Longer observation periods are required for patients with more severe reactions. You will usually spend about half the day at our clinic for an OFC.
What are the post-test instructions?
If the OFC did not cause symptoms we recommend that your child starts regularly consuming the food challenged at home, twenty four hours following the oral food challenge. The food should be a routine part of the diet. Having symptoms after a "passed" OFC is uncommon. However; if the food is not eaten in the diet regularly, your child may become allergic to it again. We will talk to you about how regularly your child should eat the food at home to avoid this occurring.
If the OFC results in an allergic reaction, then we recommend you continue to avoid this food in your child’s diet.
What are the OFC risks?
The risks of OFC include an allergic reaction including anaphylaxis. There is no evidence that having an allergic reaction during an OFC makes future reactions worse or prolongs allergy in children.
What are the benefits?
The benefits include the nutritional and social benefits of being able to expand your child’s diet if the food challenged is successfully eaten without symptoms. Even if the food triggers a reaction, the benefit is knowing that the food is truly a problem and needs to be avoided in your child’s diet.
(Adapted from American Academy of Allergy, Asthma and Immunology)
