Irritable Bowel Syndrome


  • Relapsing abdominal pain with bloating, flatulence and change in bowel habits (alternating diarrhea and constipation) that improves with defecation, seen in middle aged women.
  • This condition is a diagnosis of exclusion

Etiology and association

  • Unknown etiology, mostly women with history of childhood abuse.
  • Unknown cause of increase in frequency of normal peristalsis and segmentation contraction of bowel.
  • Can be diarrhea predominant, Constipation predominant or both (alternate consti-diarrhea).

Symptoms and Clinical Presentation:

  • Abdominal pain/cramping with change in bowel movements that gets better post defecation
  • 20% constipation only, some diarrhea alone only, rest switch between diarrhea and constipation
  • All have abdominal pain/bloat/gas/flatulence.
  • No Bleeding, No Weight loss, No fever, No nocturnal Symptoms. No GI Pathology appreciated
  • Get better with Fiber rich foot or go away with bowel movements


  • (Rome criteria) – (at least 3 months; 3 days per month) 2/3 below.
    • Change in Form and Appearance of Stool
    • Diarrhea alternating with constipation [ie change in frequency]
    • Pain relived by BM or by change in bowel habit (when you diarrhea, pain gone)
  • Colonoscopy – normal mucosa
  • Stool guaic negative, No WBC, Culture/Ova all negative, Abdominal CT negative

Treatment and Management

  • Best initial: High fiber diet and increase the bulk of the stool (help relief pain, if not use medication)
  • Medication for pain of IBD
  • Pain (antispasmotics) – Hyoscyamine, Dicyclomine, Belladonna alkaloid [relax bowel]
    • Relax muscle wall contracture hence diminish pain – Can worsen GERD!
    • If refractory pain can use TCA (anti HAM) can relax bowel and treat depression since many have depression anyways (amitriptyline is anticholinergic, relive neuropathic pain, antidepressant)
  • Medication for Diarrhea-Constipation predominant;
    • Diarrhea predominant
      • Rifaximine: non-absrobed Abx
      • Loperamide, Diphenoxylate,
      • Alosetron (arrest stool via 5HT)
      • EluxadolineL mu-opioid receptor agonist for diarrhea, relieves pain/slows bowel.
    • Constipation predominant
      • Always Fiber
      • Polyethylene glycol (PEG): non-absorbed bowel lubricant. If don’t work use below 2: lubipristone, Linaclotide
      • Lubiprostone (Cl channel activator that increase BM frequency)
      • Linaclotide (guanylate cyclase agonist) also like lubirpistone used if PEG not work.
      • Tegaserod (Side effects include diarrhea. This drug manipulate 5HT),


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