What is the recommended dosage of Senna (generic name: Sennosides) for a patient with constipation?

Senna Dosage for Constipation

For adults with chronic idiopathic constipation, start senna at 8.6–17.2 mg daily (equivalent to 1-2 tablets) and titrate upward based on symptom response, with a recommended maximum of 4 tablets twice daily (approximately 34.4 mg twice daily). 1

Initial Dosing Strategy

• Begin with 8.6–17.2 mg once daily (typically taken at bedtime), which represents the evidence-based starting dose from the 2023 AGA-ACG guidelines 1
• The FDA-approved dosing for liquid formulations is 2-3 teaspoons (10-15 mL) once daily for adults, with a maximum of 3 teaspoons (15 mL) twice daily 2
• For children 6-12 years: 1 to 1.5 teaspoons (5-7.5 mL) once daily, maximum 1.5 teaspoons twice daily 2
• For children 2-6 years: 0.5 to 0.75 teaspoons (2.5-3.75 mL) once daily, maximum 0.75 teaspoon once daily 2

Dose Titration and Optimization

• Titrate the dose upward based on symptom response and tolerability, with no absolute maximum dose specified in guidelines, though practical maximum is 4 tablets twice daily 1
• The guideline-recommended approach is to start at a lower dose than used in clinical trials and increase if there is no response, as trial doses (8.6-17.2 mg daily) are higher than commonly used in practice 1
• In pediatric protocols, doses have been successfully titrated up to 175 mg daily when needed, with an average effective dose of 67 mg (range 5-175 mg) 3
• Adjust daily during the first week based on clinical response until achieving one non-forced bowel movement every 1-2 days 1

Clinical Context and Positioning

• Senna receives a conditional recommendation (not strong) from the AGA-ACG with low certainty of evidence, meaning it should be used with shared decision-making 1
• Position senna as a first-line over-the-counter option alongside other stimulant laxatives like bisacodyl, or as rescue therapy 1
• For palliative care patients with weeks to days of life expectancy, use 2-3 tablets twice to three times daily (senna ± docusate) with goal of one non-forced bowel movement every 1-2 days 1
• In patients with anorectal malformations, senna demonstrated superior effectiveness compared to polyethylene glycol, with maximum daily doses around 38.7 mg 4

Important Safety Considerations and Pitfalls

• Common side effects include abdominal pain, cramping, and diarrhea, which are dose-dependent and typically occur at higher doses 1
• Perineal blistering is a rare but important adverse effect (2.2% incidence in one pediatric series), occurring primarily with high doses (≥60 mg/day), nighttime accidents, or prolonged stool-to-skin contact 5
• To prevent blistering: educate families to change diapers frequently and avoid prolonged skin exposure to stool 5
• Long-term safety data is reassuring: no evidence of tolerance development, no association with cathartic colon, and no carcinogenic or significant genotoxic risk even with chronic use 6
• While guidelines note "long-term safety and efficacy unknown," available evidence from chronic use studies shows senna is safe even at doses up to 300 mg/kg/day in rats for two years 6

Duration of Therapy

• Clinical trials evaluated senna for 4 weeks, but longer-term use is probably appropriate based on safety data 1
• The guidelines acknowledge that while short-term data (4 weeks) exists, extended use appears reasonable though more data would be helpful to understand tolerance and side effects 1
• Senna can be used as short-term therapy, rescue therapy, or in combination with other agents for chronic idiopathic constipation 1

Cost and Accessibility

• Senna is highly cost-effective at less than $50 per month, making it one of the most affordable laxative options 1
• Available without prescription, though dosing in laxative teas may be difficult to calculate 1