Chinese herbal medicine versus probiotics for irritable bowel syndrome: A systematic review and meta-analysis of randomized controlled trials

Introduction: Chinese herbal medicine (CHM) and probiotics are two complementary and alternative approaches often used for irritable bowel syndrome (IBS). This study evaluates the efficacy and safety of CHM compared with probiotics for IBS.Methods: 11 databases were searched (up until March 2020) for randomized controlled trials of IBS. Risk of bias was evaluated and RevMan 5.3 was used for data synthesis. Trial sequential analysis (TSA) was used to control for risk of random errors.Results: A total of 47 trials were included in the analysis. Unclear risk of bias was observed for most domains of included trials. CHM had advantages over probiotics for improving overall symptoms of IBS-Diarrhea (IBS-D) (RR 1.24, 95 % CI 1.18-1.30, 3207 patients, I-2 = 55 %, very low certainty). The heterogeneity may be associated with different diagnostic criteria, duration of treatment, probiotic composition and types of CHM. CHM may provide better outcomes than probiotics when the duration of treatment is more than 4 weeks (RR 1.26, 95 % CI 1.20-1.33, 2669 patients, very low), and the formulae represented by Tongxie Yaofang appeared to be better than triple Bifidobacterium preparations for improving overall symptoms of IBS-D (RR 1.33, 95 % CI 1.20-1.47, 476 patients). CHM may reduce relapse rate compared with probiotics (RR 0.27, 95 % CI 0.18-0.40, 382 patients, very low). Adverse events were mainly gastrointestinal symptoms.Conclusions: Very low quality evidence suggests that CHM may be better than probiotics for improving overall symptoms of IBS-D when the duration of treatment lasted more than 4 weeks; and CHM may be better than probiotics for reducing relapse rates of IBS-D.