# Nasal allergen challenge with dissolved birch tree pollen tablets

## TL;DR

This study shows that dissolved birch pollen tablets can effectively replace a discontinued allergen solution for nasal allergy testing.

## Contribution

The study demonstrates that dissolved birch pollen tablets are a feasible and reliable alternative to a discontinued allergen extract for nasal allergen challenges.

## Key findings

- Dissolved ITULAZAX tablets showed 96% sensitivity in nasal allergen challenges.
- The method achieved 95% specificity in distinguishing allergic from non-allergic responses.
- The tablets are a reliable and accessible alternative to the discontinued allergen extract.

## Abstract

The nasal allergen challenge (NAC) is a valuable diagnostic tool for both clinicians and researchers in the field of allergy and its management. In Europe, an aqueous extract Aquagen SQ (ALK-Abelló) was historically the most widely used solution for this purpose. Its production ceased in 2019, creating a gap in available resources. This clinical trial evaluated the feasibility of using dissolved birch pollen tablets, ITULAZAX 12-SQ Bet (ALK-Abelló) tablets as an alternative for NAC. A total of 69 participants with confirmed birch pollen allergy and 20 healthy controls underwent NAC using either dissolved ITULAZAX, dissolved placebo tablets, or a 0.9% saline solution. The primary objective was to assess the sensitivity of NAC with dissolved ITULAZAX. The method demonstrated a sensitivity of 96% and a specificity of 95%. These findings support the use of dissolved ITULAZAX as a reliable and accessible allergen source for nasal allergen challenges in both clinical practice and research.

The online version contains supplementary material available at 10.1038/s41598-025-27356-4.