Supplementary Material for: Herbal Medicine for Cough: a Systematic Review and Meta-Analysis

<b><i>Background:</i></b> The aim of this review was to systematically assess the literature on herbal medicine for cough as a symptom of upper respiratory tract infections and common cold. <b><i>Methods:</i></b> The Cochrane Library, Scopus, MEDLINE/PubMed, and Embase were searched through March 2012 for RCTs testing the effects of herbal medicine for cough. Risk of bias was assessed using the Cochrane tool. <b><i>Results:</i></b> 34 RCTs (N = 7,083) on <i>Pelargonium sidoides</i> (11 RCTs), <i>Echinacea</i> (8 RCTs), <i>Andrographis paniculata</i> (6 RCTs), ivy/primrose/thyme (4 RCTs), essential oils (4 RCTs) and bakumondoto (1 RCT) were included. Controls were mainly placebo. Most studies had a low risk of bias. The meta-analysis revealed strong evidence for <i>A. paniculata</i> (SMD = -1.00, 95% CI = -1.85, -0.15; P<0.001) and ivy/primrose/thyme (RR = 1.40, 95% CI = 1.23, 1.60; P<0.001) in treating cough; moderate evidence for <i>P. sidiodes</i> (RR = 4.60; 95% CI = 2.89,7.31; P<0.001), and limited evidence for <i>Echinacea</i> (SMD = -0.68; 95% CI = -1.32, -0.04; P = 0.04). <b><i>Conclusion:</i></b> This review found strong evidence for <i>A. paniculata</i> and ivy/primrose/thyme-based preparations and moderate evidence for <i>P. sidoides</i> being significantly superior to placebo in alleviating the frequency and severity of patients' cough symptoms. Additional research, including other herbal treatments, is needed in this area.