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Ask the allergist – Questions about oral food challenges

Dr. Julia Upton

Ask the allergist is our newest segment where Dr. Julia Upton answers your top questions about food allergy. Dr. Upton is a Canadian allergist who is on staff at Toronto’s SickKids Hospital in the Immunology and Allergy Department. She is an Assistant Professor in the Department of Paediatrics at the University of Toronto and is the Section Chair of Food Allergy and Anaphylaxis with the Canadian Society of Allergy and Clinical Immunology (CSACI). She is also one of Food Allergy Canada’s healthcare advisory board members.

Please note: Dr. Upton is answering as an individual allergist and her answers do not constitute an official position of her affiliated organizations. Her responses are for informational purposes only and do not constitute medical advice, recommendations, diagnosis, or treatment. Please talk to your doctor about any concerns or questions you may have regarding your own health or the health of your child.

This month she answers your questions about oral food challenges.


How does an allergist decide when and if an oral food challenge is safe or necessary?

An oral food challenge (OFC) is a test performed in a medical facility under the supervision of an allergist to prove that someone is allergic to a particular food, or to show that they are not allergic (or no longer allergic).

An allergist in clinical practice (rather than research) usually offers an OFC when they think there is a reasonable chance that the person is not allergic or has outgrown an allergy. Many factors are taken into consideration including history of allergic reactions (possible trigger, timing, severity), asthma, test results and willingness to re-incorporate the food. Please speak to your allergist about whether an OFC is right for you/your child.

How should I prepare my child for an oral food challenge?

On the day of the OFC, the child needs to be healthy. If they have asthma, it needs to be well controlled, and usually the allergist will ask you not to give them any anti-histamines several days prior to testing because they want to see the very first signs of an allergic reaction if it happens.

For more tips on how to speak to your child about oral food challenges, check out this article we did last year.

When is the appropriate age for OFCs?

OFCs can be performed at any age.

If a child tests positive for allergy but has never ingested the food, should an OFC be conducted or is home introduction an option?

Your allergist will decide on the location (hospital or office) based on the likelihood of a reaction. They will consider test results, presence of asthma and the parent’s comfort level introducing an allergenic food at home (vs office).

If there is no history of ingestion, the risk of being allergic is mainly determined by the test results. The higher the test results (e.g. larger wheal on a skin prick test), the more likely it is that the person is actually allergic. The allergist will also take into account other allergic history, for example if the person has asthma, to decide if an oral food challenge is appropriate.

Home introduction is advised when the risk of being allergic to the food is thought to be very, very low and the family is comfortable introducing the food. Therefore, home introductions are often used when test results are negative or very low. Your allergist will likely provide advice about how to introduce the food and which symptoms to look out for.

Thank you Dr. Upton for your valuable insight and taking the time to answer the top questions on oral food challenges!


Additional resources


Do you have a question you’d like to ask Dr. Upton in the months to come? If so, please send it along to us at info@foodallergycanada.ca.