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Stimulant Laxative — Bowel Preparation / Post-operative Pregnancy: Use with caution; prefer osmotic laxatives in pregnancy

Bisacodyl

Brand names: Dulcolax

Adult dose

Dose: 5-10 mg oral at night; 10 mg PR (suppository)
Route: Oral / Rectal (suppository)
Frequency: Once daily at night (oral); single dose (suppository)
Max: 20 mg/day (oral); 10 mg/day (PR)
Bowel preparation (adjunct): 10 mg oral the evening before combined with other preparation. Post-operative constipation: 10 mg oral at night once diet resumed

Paediatric dose

Dose: Fixed dose by age mg/kg
Route: Oral / Rectal
Frequency: Once daily
Max: 10 mg/day
Child 4-17 years: 5-10 mg oral once at night. Suppository: child 4-11 years: 5 mg; child 12 years and over: 10 mg. Not recommended under 4 years

Dose adjustments

Renal

No dose adjustment required

Hepatic

No dose adjustment required

Paediatric weight-based calculator

Child 4-17 years: 5-10 mg oral once at night. Suppository: child 4-11 years: 5 mg; child 12 years and over: 10 mg. Not recommended under 4 years

Clinical pearls

  • Bisacodyl is a prodrug — converted to active metabolite (BHPM) by intestinal bacteria; stimulates colonic motility and reduces water absorption; onset 6-12 hours oral, 15-60 minutes rectal
  • Enteric-coated tablets: swallow whole without chewing; do not take with milk or within 1 hour of antacids — premature dissolution in stomach causes gastric irritation
  • Post-operative bowel care: stimulant laxative (bisacodyl or senna) + osmotic laxative (macrogol or lactulose) is standard for opioid-induced constipation — always prescribe laxative when initiating regular opioids
  • Suppository: fastest onset of all oral/rectal laxatives — useful in acute post-operative constipation or when oral route unavailable
  • Tolerance develops with prolonged use — reserve for short-term use or adjunct in opioid-induced constipation; macrogol preferred for ongoing chronic constipation management

Contraindications

  • Acute inflammatory bowel conditions
  • Intestinal obstruction
  • Dehydration with electrolyte imbalance
  • Abdominal pain of unknown cause

Side effects

  • Abdominal cramps (common)
  • Diarrhoea
  • Nausea
  • Hypokalaemia (prolonged use)
  • Suppository: rectal irritation and burning

Interactions

  • Milk or antacids (dissolve enteric coating prematurely — do not take within 1 hour of bisacodyl oral)
  • Diuretics (additive hypokalaemia risk)

Monitoring

  • Bowel function
  • Electrolytes (prolonged use)
  • Signs of obstruction

Reference: BNFc; BNF 90; Dulcolax SPC; NICE NG90; ERAS Society Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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