Betahistine for residual dizziness after canalith repositioning in benign paroxysmal positional vertigo: a systematic review of randomized controlled trials

Background Benign paroxysmal positional vertigo (BPPV) is the most common peripheral vestibular disorder. Although canalith repositioning maneuvers (CRMs) are highly effective, a substantial proportion of patients experience residual dizziness (RD) after successful repositioning. Betahistine has been proposed as an adjunctive therapy to facilitate recovery; however, its effectiveness in RD remains uncertain. Aims To evaluate the efficacy and safety of betahistine in adults with BPPV who experience residual dizziness after canalith repositioning maneuvers. Methods A systematic review was conducted in accordance with the PRISMA 2020 guidelines. PubMed/MEDLINE, Scopus, and Web of Science were searched from inception to 1 February 2026. Randomized controlled trials including adults with BPPV who were treated with CRMs and presented with residual dizziness were eligible. Betahistine administered as adjunctive therapy was compared with placebo, no treatment, maneuver alone, or other pharmacological interventions. Two reviewers independently performed study selection, data extraction, and risk of bias assessment using the JBI checklist. Due to heterogeneity, findings were synthesized narratively. Results Four randomized controlled trials published between 2012 and 2022, including approximately 418 participants, were included. Betahistine daily doses ranged from 36 to 48 mg/day, with treatment durations of 1–4 weeks. Outcomes assessed included symptom intensity (VAS), disability (DHI), participation measures, duration of RD, and clinical resolution. Two trials reported significant improvements in symptom reduction, disability scores, or probability of RD resolution with betahistine, whereas two studies found no clear differences in primary outcomes or final clinical resolution compared with controls. Methodological quality varied, with one study considered at low risk of bias and three presenting uncertainties in key domains. Conclusion Betahistine may provide symptomatic or functional improvement in selected patients with residual dizziness after CRMs, but current randomized evidence remains limited, heterogeneous, and methodologically uncertain. Routine or universal use is not supported. Further adequately powered trials with standardized RD definitions, comparable outcomes, longer follow-up, and objective vestibular assessments are needed to clarify its clinical role. Systematic Review Registration https://www.crd.york.ac.uk/PROSPERO/view/CRD420261339853 .