Clinical Effects and Safety of Zhi Sou San for Cough: A Meta-Analysis of Randomized Trials

INTRODUCTION: Zhi Sou San (ZSS), a traditional Chinese prescription, has been widely applied in treating cough. The purpose of this meta-analysis was to evaluate the effectiveness and safety of ZSS for cough. METHODS: We searched relevant articles up to 5 March 2017 in seven electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, PubMed, Chinese National Knowledge Infrastructure (CNKI), Cqvip Database (VIP), China Biology Medicine disc (CBM), and Wanfang Data. Randomized controlled trials (RCTs) were eligible, regardless of blinding. The primary outcome was the total effective rate. RESULTS: Forty-six RCTs with a total of 4007 participants were identified. Compared with western medicine, ZSS significantly improved the total effective rate (OR: 4.45; 95% CI: 3.62–5.47) and the pulmonary function in terms of FEV1 (OR: 0.35; 95% CI: 0.24–0.46) and decreased the adverse reactions (OR: 0.05; 95% CI: 0.02–0.01) and the recurrence rate (OR: 0.30; 95% CI: 0.16–0.57). However, there was no significant improvement in the cough symptom score comparing ZSS with western medicine. CONCLUSIONS: This meta-analysis shows that ZSS has significant additional benefits and relative safety in treating cough. However, more rigorously designed investigations and studies, with large sample sizes, are needed because of the methodological flaws and low quality of the included trials in this meta-analysis.