SLIT Determined to be Safe and Effective in Older Children with a History of Severe Reactions


Oral Immunotherapy (OIT) is a process in which patients ingest increasing quantities of allergens (the buildup) until they can tolerate a maintenance dose. They then must consume a fixed amount of the allergen on an ongoing basis to maintain their tolerance (OIT maintenance).

OIT has been shown to be safe and effective in preschoolers, but the risk of severe reactions is higher in older children and adults. For many older kids, the strict regimen surrounding updosing — which requires many supervised visits to the allergist — and the requirements to avoid exercise and strenuous activity after dosing prove to be too restrictive.

A recent study funded by BC Children’s Hospital and published in The Journal of Allergy and Clinical Immunology: In Practice looked at the effectiveness of Sublingual Immunotherapy (SLIT) in pediatric patients 4-18 years of age. With SLIT, drops containing the allergen in solution are placed under the tongue as opposed to ingested, thus bypassing the GI tract while still desensitizing the patient to the allergen. SLIT has been shown to be safer and better tolerated than OIT, with somewhat lower effectiveness.

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Between the summer of 2020 and the winter of 2023, 188 patients with a history of moderate to severe reactions were enrolled in multi-allergen SLIT with a median age of 11 years. Over the course of 3-5 nurse-supervised visits spaced 4 weeks apart, patients built up to a 2mg SLIT maintenance dose.

Of the cohort, four patients (2.10%) required epinephrine during the updosing phase and went to the emergency department, but none experienced severe (Grade 4) reactions.

After 1-2 years of daily SLIT maintenance, patients were offered low-dose Oral Food Challenges (OFCs) with a cumulative dose of 300mg for each treated allergen.

Between June, 2022 and November, 2023, 50 OFCs were performed on 20 patients for their variety of treated allergens. Thirty-five of 50 (70%) low-dose OFCs were successful and those patients were instructed to start daily 300mg OIT maintenance; an additional 9 OFCs that were unsuccessful were counseled to self-escalate from 80mg (or higher) to 300mg at home with medical guidance as needed. This translates to 44 food challenges (88%) able to transition to OIT maintenance without the need for medically supervised buildups.

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Five patients whose reactions were more significant (with one requiring epinephrine) and one who was not comfortable completing the challenge due to anxiety were counseled to continue SLIT for another 1-2 years before repeating the low-dose OFC.

Given the results from the OFCs combined with the safety profile of the SLIT protocol — with no life-threatening reactions and few reactions requiring epinephrine — the researchers concluded SLIT was a safe and effective way to bypass the OIT buildup phase without the need for dozens of in-person visits with an allergist in children for whom OIT is considered higher-risk.

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Dave Bloom
Dave Bloom
Dave Bloom is CEO and "Blogger in Chief" of

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