Irritable Bowel Syndrome

General Medicine

Functional disorder with recurrent abdominal pain ≥1 day/week for 3 months, related to defecation and stool change (Rome IV).

History taking

  • Onset, duration, progression, severity
  • Aggravating / relieving factors
  • Past history, drugs, allergies, comorbidities
  • Family & social history relevant to presentation

Examination

  • General: vitals, pallor, icterus, oedema, lymphadenopathy
  • Focused system examination
  • Look for red-flag findings

Red flags

  • Age >50, weight loss, PR bleed, nocturnal symptoms, anaemia, family CRC

Differential diagnosis

  • See differentials section per chief complaint

Recommended investigations

  • CBC, CRP, coeliac serology, faecal calprotectin
  • TSH if diarrhoea

Diagnosis

  • Clinical diagnosis supported by targeted investigations

Initial treatment / management

  • Reassurance + dietary modification (low FODMAP trial)
  • Probiotics 4 weeks
  • Targeted symptom treatment

Drug therapy

  • Constipation: ispaghula, PEG; linaclotide if refractory
  • Diarrhoea: loperamide
  • Pain: mebeverine 135 mg TDS, peppermint oil; low-dose TCA

Follow-up advice

  • Review in 2–4 weeks or earlier if worsening
  • Monitor response to therapy and adverse effects

Patient counselling

  • Explain diagnosis and natural course in lay terms
  • Red-flag symptoms warranting urgent return
  • Adherence to medications and follow-up

Referral criteria

  • Refer if diagnostic uncertainty, complications, or failure of first-line therapy

References

  • Harrison's Principles of Internal Medicine, 21e
  • NICE / WHO guidelines (current edition)

Educational outpatient guide — verify against local guidelines before clinical use.

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