A Pilot Study of the Effectiveness of a Short Course of Rifaximin 2200 mg/day on Abdominal Symptoms and its Effects on Quality of Life in Patients with Moderate to Severe Diarrhea-Predominant Irritable Bowel Syndrome

Rifaximin is used to treat diarrhea-predominant irritable bowel syndrome (IBS-D). However, determining the most effective regimen remains a challenge. This study aimed to evaluate the effectiveness and safety of a 10-day high-dose course of rifaximin (2200 mg/day) and its effects on both abdominal symptoms and quality of life (QOL) in patients with IBS-D.

Adult patients with moderate to severe IBS-D (Rome IV) and fecal urgency and bloating were prescribed rifaximin 1100 mg twice daily for 10 days. Demographic information, the IBS Symptom Severity Index (IBS-SSI) score (using a 7-point Likert scale), and Bristol Stool Scale (BSS) score were recorded at baseline, day 10, and 4 weeks after treatment cessation. IBS Symptom Severity Score (IBS-SSS) and IBS-QOL scores were recorded at baseline and day 10. Any drug adverse effects were recorded.

In total, 39 patients completed the study. Average scores for all abdominal symptoms and BSS showed significant improvement at day 10 and 4 weeks after treatment cessation (all p < 0.001). A significant improvement was seen in IBS-SSS and overall IBS-QOL score at day 10 (p < 0.001), with the highest improvement (31%) in interference with activity. Moreover, composite improvement rates were 38.64% for all abdominal symptoms, together with BSS < 5, bi-composite (66.67% for abdominal pain + bloating; 61.54% for abdominal pain + urgency), and 56.41% for tri-composite (abdominal pain + bloating + urgency) symptoms. Notably, no serious adverse effects were reported, and the adherence rate was 94.9%.

Abdominal symptoms and overall QOL, especially in social and work dimensions, significantly improved in patients with moderate to severe IBS-D following a regimen of rifaximin 2200 mg/day, which was well tolerated.