Manage IBS with a low-FODMAP diet and symptom-specific treatments: polyethylene glycol (PEG) for IBS-C or loperamide for IBS-D. Peppermint oil capsules (0.2–0.4 mL, three times daily) may relieve abdominal pain and overall symptoms. For persistent cases, consider prescription options like rifaximin, intestinal secretagogues, or antispasmodics.
January 11, 2025

Irritable Bowel Syndrome: American College of Gastroenterology Guidelines

Evidence-Based Over-the-Counter Guide

William Shen

William Shen

Co-founder & CPO

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This guide is based on the American College of Gastroenterology 2021 Clinical Guideline for the management of Irritable Bowel Syndrome (IBS). 

IBS is a functional gastrointestinal disorder characterized by abdominal pain and altered bowel habits in the absence of detectable structural abnormalities. Not to be confused with Irritable Bowel Disease (IBD), IBS is a clinical diagnosis without findings on colonoscopy. It involves changes in gastrointestinal motility, hypersensitivity, and altered gastrointestinal permeability.

Diagnosis Criteria:

IBS is widely diagnosed with the ROME IV criteria, which state that recurrent abdominal pain must occur at least 1 day/week in the last 3 months, associated with 2 or more of the following:

  • Related to defecation.

  • Change in stool frequency.

  • Change in stool form/appearance.

First-line recommendations:

  • Lifestyle modifications: Low-FODMAP diet to reduce fermentable carbohydrate intake. Low-FODMAP Dietary Guide.

  • Constipation-predominant IBS (IBS-C) treatment: Polyethylene glycol (PEG) is an osmotic laxative that can be dissolved in water and taken as needed for short courses (1-2 weeks at a time). MiraLAX Gentle Constipation Relief (FDA NDA 22015). 

  • Diarrhea-predominant IBS (IBS-D) treatment: Loperamide slows intestinal motility to alleviate symptoms of diarrhea. Dose: 4 mg orally initially, followed by 2 mg after each loose stool (max 8 mg/day). Should not be used for > 48 hours without evaluation by a doctor. Imodium Diarrhea Relief Caplets (FDA N021855). 

Supplementary recommendations:

  • Peppermint oil: Shown across multiple randomized clinical trials to on average offer benefit for overall symptoms and abdominal pain in patients with IBS. The therapeutic dosage range studied in most IBS trials was 0.2 to 0.4 mL of peppermint oil taken three times daily in enteric-coated capsules. Peppermint Oil 50 mg Coated Softgels (FDA GRAS).

Prescription medications: 

  • Intestinal secretagogues: A group of drugs that improve colonic transit time by increasing intestinal secretion of water, bicarbonate, and chloride. Considered for the management of constipation.

  • Rifaximin: A non‑absorbable antibiotic that can be considered for diarrhea

  • Antispasmatics or tricyclic antidepressants: Can be considered to treat associated abdominal pain

Citation:

Lacy BE, Pimentel M, Brenner DM, et al. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. Am J Gastroenterol. 2020; 116(1): p.17-44. doi: 10.14309/ajg.0000000000001036

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