Irritable Bowel Syndrome¶

Hashim Hayat

Background¶

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