The efficacy of QingfengGanke granule in treating postinfectious cough in pathogenic wind invading lungs syndrome: a multicenter, randomized, double-blind, placebo-controlled trial

Background Postinfectious cough (PIC) significantly affects cough-related quality of life but still lacks effective treatments. This study aims to investigate the efficacy of QingfengGanke granule (QFGKG) in treating PIC induced by pathogenic wind invading lungs syndrome. Methods A multicenter, randomized, double-blind, placebo-controlled clinical trial was conducted. A total of 180 eligible participants were randomly (1:1:1) assigned to group A (QFGKG 6 g plus QFGKG-matched placebo 6 g), group B (QFGKG 12 g), and group C (QFGKG-matched placebo 12 g). All herbal medications were orally administered twice daily for 10 consecutive days. The primary outcome was time to cough resolution, and secondary outcomes included time to cough alleviation, mean changes in cough symptom score (CSS), visual analogue scale (VAS) score, cough-specific quality of life questionnaire (CQLQ) score, and traditional Chinese medicine (TCM) syndrome score from baseline to Day 10, as well as adverse events. Results A total of 173 participants were included in the efficacy and safety analyses (group A, n = 57; group B, n = 57; group C, n = 59). The median time to cough resolution in groups A, B, and C was more than 10 days, 8 days, and more than 10 days, respectively ( P < 0.0001), and the median time to cough alleviation was 4, 4, and 6 days, respectively ( P < 0.0001). Compared with the placebo condition, groups A and B showed significantly greater improvements in CSS ( P = 0.0005, P < 0.0001, respectively), VAS ( P = 0.0002, P < 0.0001, respectively), CQLQ ( P = 0.0258, P = 0.0003, respectively), and TCM syndrome ( P = 0.0031, P < 0.0001, respectively). The time to cough resolution was faster in group B compared with group A ( P = 0.0091). The adverse event profiles were comparable among the three groups. Conclusion QingfengGanke granule is efficacious in the treatment of PIC induced by pathogenic wind invading lungs syndrome.