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Irritable Bowel Syndrome

Hashim Hayat


  • Diagnose by the Rome IV criteria, no longer a diagnosis of exclusion
  • Recurrent abdominal pain on average at least 1 day/week in the last 3 months with an onset at least 6 months prior, associated with two or more of the following criteria
    • Pain related to defecation
    • Change in frequency of stool
    • Change in form (appearance) of stool
  • Patient has none of the following warning signs: >50yrs, evidence of GIB, nocturnal pain or BMs, unintentional weight loss, family hx of colorectal cancer or IBD, palpable abdominal mass or LAD, IDA, +FOBT
  • Classified based on predominant bowel habits
    • Diarrhea: >25% BMs with Bristol stool types 6 or 7
    • Constipation: >25% BMs with Bristol stool types 1 or 2
    • Mixed: both of above


  • Thorough H&P for alarm symptoms as above
  • Consider limited testing with CBC, CMP, CRP, celiac serology, fecal calprotectin


  • Treatment involves lifestyle and dietary modifications, psychosocial treatment, and pharmacologic treatment
  • Pain:
    • Peppermint oil (smooth muscle relaxant) – IBGuard, Iberogast
    • Antispasmodics: Hyosciamine acts faster than Dicyclomine
    • TCAs: Amitriptyline or nortriptyline (causes less constipation so better in IBS-C)
  • Bloating:
    • Low FODMAP diet
    • Rifaximin as empiric treatment for SIBO
    • No evidence for probiotics (can potentially worsen bloating 2/2 SIBO)
  • Bowel regulation:
    • IBS-D: Start with Loperamide (up to 16g daily), consider Lomotil if refractory
    • IBS-C: Miralax, fiber supplement (Ispaghula husk orange), Linzess (first line but can be expensive), Trulance, or Amitiza
  • Other
    • Psychotherapy, CBT
    • SSRIs, SNRIs for concomitant mood disorders
    • Gabapentin, lyrica