Overview
Senna, derived from the leaves and pods of Senna alexandrina, is a stimulant laxative commonly used for the short-term management of constipation. Its active compounds, sennosides, are metabolized by colonic bacteria into active aglycones that stimulate colonic motility and increase fluid secretion, promoting bowel movements [1]. Clinical studies support its efficacy in bowel preparation for colonoscopy, where regimens including senna (e.g., 180 mg tablets or 24 tablets of 12 mg) have demonstrated comparable or improved cleansing quality when combined with other agents like magnesium citrate or PEG [3][4]. Senna has also been used effectively in pediatric populations for idiopathic constipation, with dosing titrated to achieve daily bowel movements [5]. Additionally, senna glycoside has shown potential in reducing serum potassium levels in hemodialysis patients, likely by decreasing colonic potassium reabsorption [7].
Dosage Guide
Therapeutic Doses
For treatment of specific conditions
Upper Intake Limit
Maximum safe daily intake
34.4 mg— Long-term use not recommended; risk of electrolyte imbalance, melanosis coli, laxative dependence
Special Forms
Alternative forms for specific needs
Standardized extracts for consistent dosing in over-the-counter laxatives
Pod is more potent and less likely to cause cramping; preferred in formulations
Clinical Notes
- Avoid long-term use (>1 week) due to risk of electrolyte disturbances, especially hypokalemia, which may potentiate cardiac arrhythmias or interact with diuretics and digoxin
- Contraindicated in intestinal obstruction, undiagnosed abdominal pain, or inflammatory bowel disease
- Use with caution in elderly or renal-impaired patients; monitor electrolytes
- May discolor urine (yellow-brown) without clinical significance
- Animal toxicity studies show kidney weight increases and electrolyte changes at high doses (≥750 mg/kg/day), suggesting caution with excessive dosing
Research
Senna obtusifolia and Cassia sieberiana showed laxative activity in rats at 500 mg/kg, comparable to official senna leaf.
A bowel prep regimen for colon capsule endoscopy included 4 senna tablets and low-residue diet, contributing to adequate cleansing and high excretion rate.
180 mg senna tablets were as effective as sodium phosphate solution for colonoscopy preparation.
Adding senna to magnesium citrate improved colonoscopy prep quality, though not statistically significant (4% vs 7% rescheduling).
Senna-based laxatives were titrated to effect in children with idiopathic constipation, with success defined as daily bowel movements.
High-dose senna (750–1500 mg/kg/day) caused reduced weight gain, electrolyte changes, and kidney weight increases in rats over 13 weeks.
Senna glycoside significantly reduced serum potassium in hemodialysis patients (-0.32 mEq/L vs control).
High-dose senna (24 tablets of 12 mg) was comparable to 4-L PEG-ES for colonoscopy prep quality and patient acceptance.
