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Not yet taking people in ThailandPhase 3

Rifaximin Treatment in Bloating Predominant Functional Bowel Disorders

Key facts

Who runs it
Mahidol University
Where
Bangkok Noi, ThailandSee the site
Trial code
Status
Not yet recruiting
Phase
Phase 3
People taking part
78 people, planned
Starts
Dec 2026
Expected to end
Dec 2028
Type of study
Interventional, 2 groupsOne group gets a placebo (a dummy treatment), for comparison.
Treatments tested
  • Rifaximin (drug)
  • Placebo
Record updated
27 October 2026

Who can take part

Age
18 years to 80 years
Sex
Women and men
Healthy volunteers
Cannot take part

The registry criteria, word for word

Show all 11 criteriaShow less

Who can take part

  • Adults aged 18 to 80 years
  • Rome V diagnosis of irritable bowel syndrome with constipation, or functional abdominal bloating
  • Bothersome bloating with baseline severity of at least 3 on a 7-point Likert scale after adequate constipation treatment, defined as stool frequency from at least 3 times/week to 3 times/day and Bristol Stool Form Scale type 3-5
  • Colonoscopy, CT colonography, or barium enema performed if clinically indicated as part of standard evaluation for bowel symptoms

Who cannot take part

  • Current use of, or inability to discontinue, medications that may affect intestinal microbiota or gas measurements, including antibiotics, proton pump inhibitors, probiotics, lactulose, NSAIDs, or metformin
  • Current use of, or inability to discontinue, medications that may affect bloating symptoms, including simethicone, simethicone-containing antispasmodics, or antidiarrheal medications
  • History of major gastrointestinal surgery, except appendectomy or laparoscopic cholecystectomy
  • Inflammatory bowel disease or other inflammatory gastrointestinal conditions
  • Underlying conditions known to affect intestinal microbiota composition, including cirrhosis, uncontrolled diabetes mellitus, end-stage renal disease, obesity, malignancy, or psychiatric disorders
  • Known allergy to rifaximin
  • Opioid-induced constipation

Check if you might fit

Answer for yourself. This is not a decision: only the study team can say whether you can take part.

  • Are you between 18 and 80 years old?

Where in Thailand

  • Faculty of Medicine Siriraj Hospital, Mahidol UniversityBangkok Noi, ThailandContact: Monthira Maneerattanaporn, M.D.No longer taking part

About the trial

What the trial wants to find out

This randomized, double-blind, placebo-controlled trial will evaluate the effects of a 14-day course of rifaximin on bloating symptoms, gut microbiota, microbial metabolites, and intestinal gases in adults with Rome V irritable bowel syndrome with constipation (IBS-C) or functional abdominal bloating (FAB). Participants with predominant, bothersome bloating despite adequate bowel movement management will be randomly assigned in a 1:1 ratio to receive rifaximin 550 mg three times daily or matching placebo for 2 weeks. The primary endpoint is the proportion of participants with a bloating response, defined as at least a 1-point reduction from baseline on a 7-point Likert bloating scale at the end of treatment. Additional assessments will include other gastrointestinal symptoms, quality of life, psychological symptoms, gut microbiota diversity and composition, fecal short-chain fatty acids, plasma bile acids and gut-derived uremic toxins, and breath hydrogen and methane levels. Associations between biological changes and clinical response will also be examined.

The 2 groups in the trial

  • RifaximinTreatment being tested

    Participants randomized to this arm receive rifaximin 550 mg orally three times daily for 2 weeks.

    Treatment: Rifaximin (drug)

  • PlaceboPlacebo, for comparison

    Participants randomized to this arm receive an identical placebo orally three times daily for 2 weeks.

Questions to ask the study team

  1. How often do I need to come in, and for how long each time?
  2. Are travel costs paid?
  3. Can I keep my own doctor?
  4. What happens if I want to stop?

Contact the study team: see the registry record → Contacts and Locations

Print a page for my doctor

Data and sources

Registry record
Listed on ClinicalTrials.gov.
Official title
Effects of Rifaximin on Bloating, Gut Microbiome, Metabolome, and Intestinal Gas in Patients With Irritable Bowel Syndrome With Constipation or Functional Abdominal Bloating Defined by Rome V Criteria: A Randomized, Double-Blind, Placebo-Controlled Trial
Fit questions
Built from NCT07522255, who can take part
Record updated
27 October 2026