House Dust Mite Sublingual Immunotherapy for Allergic Rhinoconjunctivitis: Comprehensive Review and Meta-Analytical Evidence

INTRODUCTION: House dust mites (HDM) are a primary trigger of allergic rhinoconjunctivitis (ARC), a common condition associated with substantial symptom burden and impaired quality of life. Although sublingual immunotherapy (SLIT) with HDM extracts has shown therapeutic potential, its overall efficacy and safety profile in adults and adolescents with ARC remain incompletely defined. We aimed to assess the efficacy and safety of HDM SLIT in adults and adolescents with ARC. METHODS: We conducted a systematic search of PubMed, Scopus, Web of Science (WOS), and Cochrane CENTRAL databases up to May 2025. We included studies comparing HDM SLIT to placebo or pharmacotherapy. The main efficacy outcomes were the combined symptom and medication score (CSMS), rhinitis symptom score (RSS), rhinitis medication score (RMS), and rhinoconjunctivitis quality of life questionnaire. Safety was assessed by analyzing treatment-related adverse events (AEs), serious, severe, and local AEs. A random-effects model was used to pool standardized mean differences (SMD) and risk ratios (RR). RESULTS: A total of 45 studies involving 30,288 participants were included in the systematic review, with 28 providing data for meta-analysis. SLIT significantly improved multiple efficacy outcomes, including the RSS and RMS, with pooled SMD and 95% confidence interval (CI) (-0.98 [-1.65, -0.31], p < 0.001) and (-1.00 [-1.80, -0.20], p = 0.01), respectively. SLIT was associated with a greater risk of treatment-related AEs, with a pooled RR and 95% CI (1.16 [1.02, 1.33], p = 0.02), which were predominantly mild, local, and transient. CONCLUSION: This study confirms that standardized HDM SLIT is an effective and safe disease-modifying therapy for adults and adolescents with ARC. It provides clinically meaningful reductions in symptoms and medication use and improves quality of life. The favorable safety profile supports its use as a foundational treatment in the management of HDM-induced ARC.