Advice on Testing Toddler for Food Allergy

Published: August 31, 2011

Q. I have peanut and soy allergies and my husband gets hay fever, so I’ve been putting off introducing our son (no known allergies) to peanuts and nuts. He’s 2 ½ and going to daycare soon, so we have to start the process. My allergist is willing to skin test, but if there haven’t been exposures, would that work? What’s the safest way to go about introducing these foods with our history?

Dr. Watson: Parents are always concerned about introducing highly allergenic foods, especially if they or other children have food allergies. There is very little data in the medical literature to support any advice. You are correct that skin testing an individual who has never been exposed to a food doesn’t make much sense. False positive reactions occur up to 50 per cent of the time, so a positive test means little. The only rational is that if the test is negative, you can be relatively comfortable giving the first exposure at home, as the risk of a reaction is no greater than in the general population.

As a person with peanut allergy, you should not be the one feeding your son peanut. You can be close by. There are different options on how to introduce an allergen, but it’s generally recommended to start with a small amount of peanut butter on the lip. If that’s tolerated, then your son can try a small amount in his mouth. If he refuses to eat it, or if you are worried, don’t push him.

If he tolerates the peanut, he should eat it at least once per week, as the chance of developing an allergy to a food eaten regularly is less than if the food is eaten rarely. If the thought of this procedure keeps you awake at night, talk to your allergist about trying peanut in his or her office.

We welcome your question to Allergic Living’s Ask the Allergist. Thank you for understanding that the specialists aren’t able to answer every question received.

Dr. Wade Watson is a pediatric allergist and Professor of Pediatrics at Dalhousie University. He is also the head of the Division of Allergy at the IWK Health Centre in Halifax.

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