World Allergy Organization Sublingual Immunotherapy Position Paper: 2026 update

Background: Sublingual immunotherapy (SLIT) is a well-established form of allergen immunotherapy with demonstrated efficacy and a favorable safety profile in IgE-mediated allergic diseases, particularly in allergic rhinitis and allergic asthma. Since the publication of previous World Allergy Organization (WAO) position papers, accumulating evidence and expanding global clinical experience has justified an updated, internationally harmonized framework to guide the appropriate use of SLIT across diverse healthcare settings. Methods: An international panel of experts developed an updated Position Paper on SLIT using a structured Delphi consensus methodology. Statements were formulated based on a targeted review of the scientific literature and expert clinical experience, addressing indications, patient selection, safety, treatment duration, adherence, biomarkers, disease modification, and implementation domains. Two rounds of anonymous electronic voting were conducted. Consensus was predefined as ≥70% agreement (scores 4-5 on a 5-point Likert scale). Results: Eighty-three experts representing all WAO regions were invited, and seventy-eight of them participated in the Delphi process. High levels of consensus were achieved for core principles, including SLIT effectiveness, safety, the importance of appropriate patient selection, a minimum treatment duration of 3 years, supervised administration of the first dose followed by home-based treatment, and the central role of adherence and regular follow-up. Consensus regarding disease-modifying effects was stronger for children and adolescents than for adults. Lower consensus was observed on topics related to regional allergens, likely influenced by differences in allergen exposure, product availability, clinical experience, and regulatory contexts; however, formal region-stratified analyses were not performed. Conclusions: This WAO Position Paper establishes a globally applicable, evidence-informed consensus framework for the positioning and implementation of SLIT. By clearly delineating areas of strong agreement and domains of conditional or context-dependent evidence, it provides both a clinical reference and a strategic roadmap for equitable and sustainable SLIT integration worldwide.