Section 19 · Monograph
Senna
Reviewed Nov 2026FDA label
SenokotStimulant laxative
- Forms
- Tab: 8.6, 17.2mg | Syrup: 8.8mg/5mL
- Dose
- Opioid-induced or neurogenic constipation: 8.6-17.2mg at bedtime, up to twice daily
- MOA
- Stimulates colonic motility and secretion
Indications
- Constipation, including opioid-induced constipation, and bowel preparation (OTC)FDA-labeled
Mechanism of Action
- Sennosides are converted by colonic bacteria to active metabolites that stimulate colonic motility and fluid secretion
Full Dosing
Adult / usual
- 8.6-17.2mg PO at bedtime, up to 34.4mg twice daily
- Combine with osmotic agents (polyethylene glycol) when constipation persists; for neurogenic bowel it is often given on a scheduled program
- Start at the same time as opioid therapy
Contraindications
- Intestinal obstruction, fecal impaction with obstruction, acute abdomen
- Undiagnosed abdominal pain
Drug Interactions
- Other laxatives and diuretics: electrolyte depletion
- Digoxin: hypokalemia increases toxicity
Adverse Effects
- Abdominal cramping
- Diarrhea and dehydration
- Hypokalemia with prolonged overuse
- Urine discoloration
Monitoring Parameters
- Bowel pattern and cramping
- Hydration and electrolytes with prolonged use
Pregnancy & Lactation
- Generally considered acceptable at recommended doses
- Minimal transfer into milk