Can You Do an Oral Food Challenge With a Positive Skin Test?

Our Adventures in Oral Food Challenges Continue

by: Alex Thom
Skin Testing for Allergy Oral Challenge |

Forgive me the backstory on this one, but you'll need it to understand how we got to this point in our food allergy journey. My son is turning seven this year, and has had food allergies his entire life. He used to react to allergens through breastmilk, even though multiple doctors told me I was mistaken. Allergies were confirmed by his reactions, and then by skin tests at nine months of age. At 14 months, he had a serious reaction to tilapia and was taken to hospital by ambulance. Since then, I've dedicated much of my life to educating myself and others about the realities of food allergies, and hoped that one day our son could outgrow them.

In May, we got some very happy news from the Allergy/Immunology Clinic at SickKids: our son's not allergic to almonds! He'd been labelled as allergic to tree nuts and peanuts without ever having had reactions because of positive skin tests. Back when he was a toddler, it was still common practice to rely on skin tests to diagnose allergies, but now the recommendation is to never skin test a child who hasn't had a reaction to a food because of how inaccurate the skin tests can be. Unfortunately, our allergist felt that despite a number of exposures without reactions, our son was allergic to nuts and peanuts. So we lived with that assumption for years — better safe than sorry, and all that.

I am extremely thankful to have had the opportunity to interview Dr. Adelle Atkinson from the SickKids allergy clinic on a number of occasions because without her, I'd never have had the knowledge needed to press our allergist for a referral to SickKids for our son. Our allergist felt that because of the size of the reaction for peanuts and tree nuts on our son's skin, he wouldn't be a good candidate for oral food challenges. but then something changed. His blood work was also borderline. At our last visit, the skin test for almonds was negative so I pressed for a referral to SickKids, and got the ball rolling on the series of events that have changed our lives completely.

While at the SickKids clinic for our son's almond oral challenge, we mentioned his other exposures without reactions. That was a key point in moving to the next stage. We were sent home with instructions to do oral food challenges for the rest of the tree nuts, and booked in for a peanut oral food challenge in September. We were elated! They felt that given his history, he could be a good candidate for the peanut oral food challenge, and we were so hopeful, too. As it happened, there was a cancellation and we were able to get in even sooner, so on August 23rd, we headed back to the SickKids allergy clinic filled with hope and nervousness.

Step one was to go over his allergy history again. We talked about the one and only time (that we know of) that he ate peanut butter without a reaction. They looked at his blood test numbers, and did a skin test on him. Here was the result of his skin test:

Skin Testing for Allergy Oral Challenge |

It didn't look good. There was a lot of measuring and considering happening, and at that point, we felt that it was the end of the testing. They even called the lab to get the results from our son's last blood test, which was borderline. . . But when the allergy fellow on call conferred with the allergist, we were told they felt comfortable moving forward with the oral challenge. And we felt that if they were okay with it, we would trust them, so on we pushed.

It was the same process as the oral food challenge to almonds — starting with a very small amount of the allergen and increasing every half hour up to approximately a tablespoon. They used real peanut butter, which was a totally new texture and taste for our son. He wasn't sure he loved it, but he was very excited for the possibility of not being allergic!

Each time he was given a dose, I held my breath wondering if this would be the time he'd react. But he happily played in the waiting room, with no symptoms at all.

Skin Testing for Allergy Oral Challenge |

After just a few hours, we were given the official news: our son was no longer considered peanut allergic.

Our son is no longer considered an allergic kid. We're still working our way through the home tests for the remaining tree nuts, but we were told that given the fact that he's never reacted, he's likely not allergic.

I cannot explain this relief. I can't tell you exactly what it's like to have this weight lifted. It still feels surreal. A couple days after the test, I stood in the aisle at the grocery store with tears rolling down my cheeks because these items were in my cart for my son:

Skin Testing for Allergy Oral Challenge |

He has visited ice cream shops for the first time in his life, and eaten foods we always worried may kill him. I still can't quite believe it's true.

Skin Testing for Allergy Oral Challenge |

Despite this relief, I wonder — was our son ever actually allergic to nuts and peanuts? How many other kids are out there living in fear of contact with foods they're not allergic to? How many others relied on skin tests to predict allergies as we had?

If I can stress anything to anyone with food allergies, it's to press your allergist for up-to-date testing. If there's never been a reaction to eating a food, skin tests are simply not reliable. 

The freedom of being delabeled is truly life-changing, although I suppose it does mean I'm no longer "Irritated By Allergies," other than environmental stuff. And let me tell you — I'll take those over food allergies any day.

Skin Testing for Allergy Oral Challenge |

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