Stimulant Laxative
Pregnancy: Second-line — limited systemic absorption; use lactulose preferentially; avoid prolonged use
Senna
Brand names: Senokot, Manevac
Adult dose
Dose: 15–30 mg (2–4 tablets of 7.5 mg)
Route: Oral
Frequency: Once daily at bedtime
Max: 30 mg/day
Second-line laxative in pregnancy after osmotic laxatives (lactulose). Used post-operatively (post-caesarean, post-gynaecological surgery). Effect in 8–12 hours.
Paediatric dose
Dose: Age-based dosing mg/kg
Route: Oral
Frequency: Once or twice daily
Max: 30 mg twice daily
BNFc: 1 month–4 years 3.75–15 mg once or twice daily; 4–18 years 7.5–30 mg once or twice daily. Use lowest effective dose.
Dose adjustments
Renal
No dose adjustment required
Hepatic
No dose adjustment required
Paediatric weight-based calculator
BNFc: 1 month–4 years 3.75–15 mg once or twice daily; 4–18 years 7.5–30 mg once or twice daily. Use lowest effective dose.
Clinical pearls
- Second-line laxative in pregnancy — limited systemic absorption but some anthraquinone metabolites excreted in breast milk; use lactulose first
- Post-caesarean bowel management: senna + lactulose combination commonly used in UK practice
- Avoid prolonged use — may cause electrolyte disturbance and dependence
- Safe in breastfeeding — small amounts in breast milk do not cause laxative effects in infant at standard doses
- Manevac combines senna with ispaghula husk — useful for mixed constipation
Contraindications
- Intestinal obstruction
- Severe dehydration
- Acute inflammatory bowel conditions
Side effects
- Abdominal cramps
- Diarrhoea
- Electrolyte disturbance (prolonged use)
- Urine discolouration (harmless)
Interactions
- Digoxin — hypokalaemia from prolonged use may potentiate toxicity
Monitoring
- Symptom response
- Electrolytes (prolonged use)
Reference: BNFc; BNF 90; BNFc; NICE CG190; RCOG obstetric pharmacology guidance. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.