Using Rifaximin to treat active Microscopic Colitis

Efficacy and Safety of Oral Rifaximin in Patients With Active Microscopic Colitis

PHASE2 · Endeavor Health · NCT04043897

This study is testing if the antibiotic Rifaximin can help people with active microscopic colitis feel better and improve their symptoms.

Quick facts

PhasePHASE2
Study typeInterventional
Enrollment10 (estimated)
Ages18 Years and up
SexAll
SponsorEndeavor Health (other)
Locations1 site (Evanston, Illinois)
Trial IDNCT04043897 on ClinicalTrials.gov

What this trial studies

This open-label, single-arm trial evaluates the efficacy of Rifaximin in patients diagnosed with active microscopic colitis, specifically collagenous or lymphocytic colitis. A total of 10 subjects will receive 500mg of Rifaximin three times daily for four weeks. The primary endpoints include histologic response and clinical remission, defined by stool frequency and consistency. Secondary endpoints will assess changes in the Microscopic Colitis Disease Activity Index (MCDAI).

Who should consider this trial

Good fit: Ideal candidates are individuals diagnosed with collagenous or lymphocytic colitis experiencing active flare-ups.

Not a fit: Patients without a confirmed diagnosis of microscopic colitis or those not experiencing active symptoms may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could provide a new therapeutic option for patients suffering from active microscopic colitis.

How similar studies have performed: While this approach is novel for microscopic colitis, similar studies using Rifaximin for other gastrointestinal conditions have shown promising results.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Collagenous colitis (CC) or lymphocytic colitis (LC) diagnosed on colon biopsies reviewed by 2 separate pathologists
* CC will be defined histologically to be the following: thickness of the collagenous subepithelial table \>10 micrometer using an ocular micrometer, inflammation in the lamina propria consisting of mainly lymphocytes and plasma cells, lack of crypt architectural distortion, and regenerative-appearing changes in the surface and/or crypt epithelium
* LC will be defined histologically to be the following: intraepithelial lymphocytes \>20 per 100 epithelial cells in the subjective area of highest lymphocyte density, inflammation in the lamina propria consisting of mainly lymphocytes and plasma cells, and regenerative-appearing changes in the surface and/or crypt epithelium
* Subjects in active flare, defined as \>3 watery/loose stools per day on \>4 / 7 days over \>4 weeks in the past 3 months.

Exclusion Criteria:

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Where this trial is running

Evanston, Illinois

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Microscopic Colitis

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.