NCT06684470 · Mayo Clinic
Novel Pilot Study to Treat Symptoms of IBS With Diarrhea Using Combination Therapy of a Low-FODMAP Diet and a Neuromodulator
What this study is about
The purpose of this research is to study the added benefit of treating IBS symptoms with a medication called mirtazapine in treating IBS symptoms when paired with a low-FODMAP diet compared to a low-FODMAP diet alone. FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. These are short-chain carbohydrates that can cause digestive distress in some people.
View original scientific description
The purpose of this research is to study the added benefit of treating IBS symptoms with a medication called mirtazapine in treating IBS symptoms when paired with a low-FODMAP diet compared to a low-FODMAP diet alone. FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. These are short-chain carbohydrates that can cause digestive distress in some people. You have been asked to take part in this research because you have symptoms of diarrhea-predominant irritable bowel syndrome that may respond to treatment with a combination of a medication called mirtazapine and a low-FODMAP diet.
Interventions
DRUG
Mirtazapine
mirtazapine will be told to use 1 pill 1 hour before bedtime for the first week (7.5 mg po q.h.s.), 2 pills before bedtime during the second week of therapy (15 mg po q.h.s.), 3 pills (22.5 mg po q.h.s.) 1 hour before bedtime for the third week, and 4 pills (30 mg po q.h.s.) 1 hour prior to bedtime for the remainder of the study.
OTHER
Placebo
Placebo will be told to use 1 pill 1 hour before bedtime for the first week (7.5 mg po q.h.s.), 2 pills before bedtime during the second week of therapy (15 mg po q.h.s.), 3 pills (22.5 mg po q.h.s.) 1 hour before bedtime for the third week, and 4 pills (30 mg po q.h.s.) 1 hour prior to bedtime for the remainder of the study.
Primary outcome measures
Resolution of Irritable Bowel Syndrome
Time frame: 49 days
Evaluate global improvement in IBS symptoms using the validated IBS-SSS
Abdominal Pain Score
Time frame: 49 days
Assess improvement in abdominal pain using a numerical rating system
Stool Form Scale
Time frame: 49 days
Assess improvement in diarrhea using the Bristol stool form scale
Mayo Bloating Scale
Time frame: 49 days
Assess response to bloating using a validated Mayo bloating questionnaire
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Participants must meet all of the inclusion criteria to participate in this study:
- Adults (ages 18-70)
- Score of \>175 on the IBS-SSS questionnaire
- Must meet Rome IV criteria for IBS-D
- If subject is of reproductive capability a negative urine pregnancy test must be available prior to entering the study
- Ability to understand study procedures and to comply with them for the entire length of the study
Exclusion criteria
- All candidates meeting any of the below exclusion criteria at baseline will be excluded from study participation:
- Score of \< 175 on the IBS-SSS
- Prior diagnoses of: known celiac disease, small intestinal bacterial overgrowth, inflammatory bowel disease, or microscopic colitis
- Ongoing significant anxiety or depression
- A history of a known side effect to mirtazapine
- Prior treatment with a low FODMAP diet or mirtazapine without clinical benefit
- Active alcohol or drug abuse
- Inability to read or understand the consent form
- Any other medical or psychological reason that would prevent active participation in a research study
- Pregnant females
Where
- Jacksonville, Florida
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Dec 18, 2025 · Source of record for eligibility and locations