A Meta-Analysis of the Therapeutic Effects of Capsaicin in Patients with Chronic Cough

Objective: This study aimed to assess the efficacy of inhaled topical capsaicin versus placebo in reducing cough frequency and cough sensitivity scores in patients with chronic cough. To address this objective, a systematic review and meta-analysis of randomized controlled trials (RCTs) were performed. Methods: Web of Science, Embase, PubMed, Cochrane Library, CNKI, Weipu, and Wanfang were searched for RCTs evaluating capsaicin for the treatment of chronic cough. Studies were screened, their quality assessed, and data extracted; those that failed to meet the inclusion criteria were excluded. A systematic review and meta-analysis were then performed on the eligible studies. Results: This meta-analysis was prospectively registered in PROSPERO. A total of five highquality RCTs were included. Compared to the control group, there was a statistically significant reduction in cough frequency (Z=18.52, P<0.00001, 95% CI: 2.09-2.59). Additionally, the difference in cough sensitivity scores was also statistically significant (Z=18.88, P<0.00001, 95% CI: 1.33-1.65). Discussion: While the results of this meta-analysis suggest that capsaicin may have a beneficial effect on chronic cough, the findings are limited by the small number of trials and the relatively small sample sizes included in the analysis. Conclusion: Capsaicin represents a novel therapeutic strategy for chronic cough, suggesting it a non-traditional antitussive treatment. Further well-designed, large-scale randomized controlled trials are needed to confirm its efficacy, elucidate its long-term mechanisms, and support the development of standardized clinical guidelines.