Adult Senna Liquid Dosing
For adults taking senna liquid, start with 2-3 teaspoons (10-15 mL) once daily at bedtime, with a maximum dose of 3 teaspoons (15 mL) twice daily. 1
Initial Dosing Strategy
- Begin with 2-3 teaspoons (10-15 mL) once daily at bedtime as the standard starting dose for adults, which corresponds to approximately 8.6-17.2 mg of sennosides 1, 2
- The FDA-approved liquid formulation allows for precise dose titration compared to tablets, which typically contain 8-9 mg per tablet 3
- Take at bedtime to allow the 6-12 hour onset of action to produce a morning bowel movement 3
Dose Titration and Maximum Limits
- Maximum dose is 3 teaspoons (15 mL) twice daily (total 30 mL/day), though most patients will not require this amount 1
- Titrate upward only if inadequate response after several days, as the trial dose of 1 gram daily (equivalent to approximately 67 mL of standard liquid formulation) proved too high for most patients 2, 3
- In the pivotal clinical trial, 83% of participants reduced their dose due to side effects, indicating that starting low is critical 3, 2
Important Clinical Considerations
Common pitfalls to avoid:
- Abdominal cramping and diarrhea occur particularly at higher doses and signal the need for dose reduction 2, 3
- Night-time diarrhea with prolonged stool-to-skin contact can cause perineal blistering in rare cases, particularly at doses above 60 mg/day 4
- Shake the liquid formulation well before each use to ensure consistent dosing 1
Duration and Monitoring
- While studied for only 4 weeks in clinical trials, longer-term use is appropriate for chronic constipation management 3, 2
- The American Gastroenterological Association conditionally recommends senna for chronic idiopathic constipation, though evidence certainty is low 3, 2
- Monitor for hypokalemia in patients on medications affecting potassium levels or those with cardiac conditions, as chronic diarrhea can cause significant electrolyte depletion 2
Mechanism and Efficacy
- Sennosides require gut bacteria for conversion to active metabolites (rheinanthrone and rhein), so antibiotics may reduce efficacy 2, 5
- Senna significantly increases complete spontaneous bowel movements by 7.6 per week compared to placebo (95% CI 5.90-9.30) 2
- Over 90% of sennosides are excreted in feces, making it safe in chronic kidney disease unlike magnesium-based laxatives 2, 6
Contraindications
- Do not use in patients with intestinal obstruction, ileus, severe dehydration, or acute inflammatory bowel conditions 3, 2
- Not recommended during pregnancy due to potential weak genotoxic effects observed in animal studies 3, 2