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NCT Number: NCT07815548

Comparison of the Efficacy of Saccharomyces Boulardii and Rifaximin in the Treatment of Small Intestinal Bacterial Overgrowth

This multicenter randomized controlled study aims to systematically evaluate the efficacy and safety of Saccharomyces boulardii sachets versus rifaximin in the treatment of small intestinal bacterial overgrowth (SIBO), with a focus on symptom relief and the impacts of anxiety-depressive factors on the treatment of abdominal distension and diarrhea in SIBO patients. The findings will offer a new non-antibiotic therapeutic option for SIBO, especially for patients with antibiotic resistance or those requiring long-term management, and lay a theoretical foundation for the clinical application of intestinal microecological regulators.

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Key information

Conditions

Small Intestinal Bacterial Overgrowth Syndrome (SIBO)

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Aged between 18 and 70 years, male or female.
  • Presenting with chief complaints of abdominal distension and/or diarrhea.
  • Diagnosis of small intestinal bacterial overgrowth (SIBO) confirmed by positive hydrogen-methane breath test.

Exclusion criteria

  • Pregnant, puerperal, or breastfeeding women.
  • Prior history of gastrointestinal malignancy or gastrointestinal surgery.
  • Previously diagnosed or suspected lactose intolerance.
  • Severe or extremely abnormal anxiety-depression scale scores.
  • Confirmed extra-digestive system diseases, including urinary system diseases (e.g., chronic kidney disease), immune system diseases (e.g., scleroderma), nervous system diseases (e.g., Parkinson's disease), and endocrine system diseases (e.g., diabetes mellitus).
  • Use of antibiotics or microecological preparations within 2 weeks before enrollment; receiving endoscopy, enema, or colonic barium-air contrast examination within 2 weeks before enrollment; use of prokinetics, secretagogues, antifoaming agents, antispasmodics, opioids, or antidepressants within 1 week before enrollment.
  • Known allergy to study medications.
  • Immunosuppressed hospitalized patients or hospitalized patients with immune impairment due to critical illness.
  • Unable or unwilling to provide written informed consent.
  • History of psychiatric disorders.
  • Any other conditions that render the subject inappropriate for participation in this study, as judged by the investigator.

Treatment and study plan

Saccharomyces boulardii sachets

Drug

0.5 g, orally, twice daily for 2 weeks

Rifaximin (Xifaxan)

Drug

0.4 g, orally, twice daily for 2 weeks

Primary outcomes

  1. Clinical Effective Rate After Intervention and 1 Month Post-treatment

    Time frame: End of 2-week treatment; 1 month after completion of treatment

    Proportion of participants achieving clinical effectiveness, defined as complete relief, major relief or partial relief of abdominal distension and diarrhea symptoms. Clinical effective rate = (number of participants with complete relief + major relief + partial relief) / total number of participants × 100%

Secondary outcomes

  1. Symptom Relief Rate After Intervention and 1 Month Post-treatment

    Time frame: End of 2-week treatment; 1 month after completion of treatment

    Symptom relief rate calculated as [(pre-treatment total symptom score - post-treatment total symptom score) / pre-treatment total symptom score] ×100%. Symptom scores for abdominal distension and diarrhea are assessed by 4-level scoring systems

  2. Change From Baseline in Gastrointestinal Symptom Rating Scale (GSRS) Total Score

    Time frame: Baseline, end of 2-week treatment, 1 month after completion of treatment

    GSRS is a 7-point Likert-type scale evaluating 15 gastrointestinal symptoms; total score ranges from 15 to 105, higher scores indicate more severe gastrointestinal symptoms. Change = post-treatment score minus baseline score

  3. Incidence of Adverse Events

    Time frame: From first study drug administration up to 60 days after last study drug dose

    Proportion of participants experiencing adverse events during the 2-week treatment period. Adverse events are graded per Common Terminology Criteria for Adverse Events Version 5.0 (CTCAE v5.0)

  4. Participant Treatment Adherence Rate

    Time frame: Throughout the 2-week treatment period

    Treatment adherence defined as actual study drug consumption accounting for 80%-120% of prescribed dose. Adherence rate = number of participants with adequate adherence / total evaluable participants ×100%

  5. Proportion of Participants With Comorbid Anxiety and Depression

    Time frame: Baseline, 1 month after completion of treatment

    Proportion of SIBO participants with abnormal anxiety-depression scores. Assessments include Self-rating Anxiety Scale (SAS), Self-rating Depression Scale (SDS), Hamilton Anxiety Rating Scale (HAMA), and Hamilton Depression Rating Scale (HAMD)

  6. Correlation Between Anxiety-depression Scores and Degree of Symptom Relief

    Time frame: Baseline, 1 month after completion of treatment

    Correlation analysis between baseline anxiety-depression scale scores and symptom relief rate after treatment

Study contacts

Contact information is provided by the study sponsor or research team.

Xiuli Zuo

CONTACT

[email protected]

+86-18560080066

Sponsors and collaborators

Lead sponsor

Shandong University

Other

Registry information

Official study title

Comparison of the Efficacy of Saccharomyces Boulardii and Rifaximin in the Treatment of Abdominal Distension and Diarrhea Related to Small Intestinal Bacterial Overgrowth：a Non-inferiority Randomized Controlled Study

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Sep 11, 2026
Registry last updated
Sep 15, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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