ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Stimulant Laxative — Constipation in Children Pregnancy: Avoid in first trimester; short courses acceptable in later pregnancy for constipation unresponsive to dietary measures and osmotic laxatives

Senna (Paediatric)

Brand names: Senokot, Ex-Lax

Adult dose

Dose: 2–4 tablets (15–30 mg sennosides) at bedtime
Route: Oral
Frequency: Once daily at bedtime
Max: 4 tablets/day
Adult reference — see paediatric dose section

Paediatric dose

Route: Oral (syrup 7.5 mg/5 mL)
Frequency: Once daily at bedtime (bowel motion expected 8–12 hours later)
Max: Age-banded
BNFc: 1 month–4 years: 2.5–10 mL syrup at night; 4–18 years: 2.5–20 mL syrup at night (adjust to response). Do not use for more than 5 days without medical review (acute constipation) — longer courses acceptable under medical supervision for chronic constipation. Not suitable for bowel obstruction. Onset 8–12 hours — give at bedtime for morning action. Often combined with softener (lactulose) in stepwise approach.

Dose adjustments

Renal

No dose adjustment required

Hepatic

No dose adjustment required

Clinical pearls

  • Stimulant vs osmotic laxatives: senna stimulates colonic peristalsis (anthraquinone glycoside → active anthrones irritate myenteric plexus); macrogol/lactulose work osmotically — different mechanisms, different onset (senna: 8–12 hours; osmotic: 12–48 hours)
  • NICE NG90: disimpaction first (macrogol high-dose), then maintenance; senna added as step-up if macrogol alone insufficient — combined osmotic + stimulant approach
  • Senna should be avoided long-term without monitoring — stimulant laxatives can cause hyponatraemia, hypokalaemia; monitor electrolytes if used beyond 2–4 weeks
  • Melanosis coli: long-term senna use causes reversible brown/black pigmentation of colonic mucosa (lipofuscin deposition in macrophages) — seen on colonoscopy; does not indicate pathology; reassure and reduce dose

Contraindications

  • Intestinal obstruction
  • Ileus
  • Dehydration with electrolyte disturbance
  • Inflammatory bowel disease (acute attack)
  • Children under 1 month

Side effects

  • Abdominal cramps (very common)
  • Diarrhoea (excess doses)
  • Electrolyte disturbance (prolonged high-dose use)
  • Melanosis coli (long-term use — reversible brown pigmentation of colonic mucosa)
  • Dependency (chronic overuse)

Interactions

  • Antiarrhythmics — electrolyte disturbance from laxative abuse may worsen arrhythmia
  • Cardiac glycosides (digoxin) — hypokalaemia from laxative overuse increases digoxin toxicity

Monitoring

  • Stool frequency and consistency (Bristol Stool Scale)
  • Electrolytes (sodium, potassium — prolonged use)
  • Abdominal examination (obstruction signs)
  • Dietary and fluid intake assessment

Reference: BNF for Children; NICE NG90 (Constipation in Children); ESPGHAN Childhood Constipation Guidelines 2014. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

Calculators
Pathways