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Table 1 Inclusion and exclusion criteria used to determine eligibility for participation

From: Open-label versus double-blind placebo treatment in irritable bowel syndrome: study protocol for a randomized controlled trial

1. Provide signed and dated informed consent and understand the nature of the study sufficiently to allow completion of all study assessments
2. Be ambulatory, community dwelling, 18 to 80 years, inclusive
3. Meet Rome IV diagnostic criteria for IBS
4. Have IBS of at least moderate severity, i.e., have a score on the IBS-SSS of >175 (0–500) at the baseline visit*
5. If the patient is on medications which affect the gastrointestinal tract or visceral sensation (e.g., tricyclic antidepressants, fiber, antispasmodics, etc.), they must be on a stable dose for at least 1 month prior to entering the study and for the duration of the study*
*Participants will be allowed to rescreen once if they do not meet inclusion criteria #4 or #5 at the initial screening visit
1. Self-reported pregnancy or planned pregnancy within the next 2 months
2. Have an established diagnosis of any concomitant bowel disturbance that would interfere with the assessment of efficacy or safety in the study (e.g., Hirschsprung’s disease, diverticulitis, colonic ischemia)
3. Report warning symptoms (e.g., rectal bleeding, weight loss >10%, iron deficiency anemia, etc.) otherwise not explained
4. Have undergone previous abdominal surgery to the intestines (with the exception of uncomplicated appendectomy, cholecystectomy, hysterectomy, or polypectomy >6 months prior to enrollment)
5. Have a history of drug, excluding nicotine or caffeine, or alcohol abuse within 2 years of entry into the study
6. Exhibit abnormalities on physical examination, unless judged to be clinically insignificant by the investigator. Such cases will be noted
7. Current, within the past 30 days, therapeutic use of enteric-coated peppermint oil for the treatment of IBS
8. Known or suspected peppermint or soybean oil allergy
9. Severe acid reflux (>3 episodes of heartburn or regurgitation per day on average over a week)
10. Inability to speak or read English
11. Unable or unwilling to cooperate with the study protocol or considered by the investigator to be unsuitable for the study
  1. IBS irritable bowel syndrome, IBS-SSS Irritable Bowel Syndrome Severity Scoring System