Efficacy of Rifaximin Combined with Probiotics in the Treatment of Functional Diarrhea: A Prospective Cohort Study

Background Functional diarrhea (FDr) is a common functional gastrointestinal disorder characterized by chronic or recurrent loose stools without organic pathology. It has a worldwide prevalence and exerts a substantial negative impact on patients’ quality of life. Current therapeutic options for FDr remain limited and are often unsatisfactory. Rifaximin is a minimally absorbed, broad-spectrum, gut-targeted antibiotic with modulatory effects on intestinal microbiota and mucosal inflammation. While rifaximin has demonstrated efficacy in irritable bowel syndrome with diarrhea, robust evidence for its therapeutic role in FDr is lacking. Aims This prospective cohort study aimed to investigate the efficacy and safety of rifaximin combined with probiotics in improving clinical symptoms and reducing recurrence in patients with FDr. Methods From April 2022 to June 2024, 121 patients diagnosed with FDr at the Department of Gastroenterology, the Second Affiliated Hospital of Soochow University, were consecutively enrolled. Patients chose either rifaximin combined with probiotics (exposed group) or probiotics alone (unexposed group). All patients received probiotics as baseline therapy, while the exposed group additionally received rifaximin. Symptom changes, including mean daily stool frequency, stool consistency, urgency, incomplete evacuation, flatulence, borborygmi, and presence of mucus or foam, were recorded at baseline, at the end of treatment, and one month after treatment. Primary outcomes were improvements in stool frequency and stool consistency. Secondary outcomes included changes in other gastrointestinal symptoms and overall response rate. Statistical analysis was performed using chi-square and paired t-tests, with P < 0.05 considered significant. Results At the end of treatment, both groups showed significant improvement compared with baseline across all evaluated symptoms. Between-group comparison demonstrated that the rifaximin group achieved significantly greater improvement in stool frequency and flatulence (P < 0.05). At one month post-treatment, partial symptom relapse was observed, but both groups maintained better outcomes compared with baseline. The rifaximin group exhibited significantly greater improvement in stool frequency, stool consistency, and flatulence than the control group (P < 0.05). The overall response rate was 87.1% versus 72.9% at treatment completion (P < 0.05) and 77.4% versus 54.2% at one month post-treatment (P < 0.05). No serious adverse events were reported. Conclusion Rifaximin combined with probiotics effectively improves stool frequency, stool consistency, and flatulence in patients with FDr, reduces recurrence, and enhances quality of life. The regimen was well tolerated and may represent a promising therapeutic option for FDr, warranting further validation in randomized controlled trials.