What is the recommended dosage and treatment duration for Senna (sennosides) in treating constipation?

Senna Dosage and Treatment Duration for Constipation

The recommended dosage of senna for treating constipation in adults is 8.6-17.2 mg daily, with a maximum of 4 tablets twice per day, and treatment duration should be guided by symptom response rather than a fixed timeframe. 1

Dosage Recommendations

Adults and Children ≥12 years:

• Initial dose: 2-3 teaspoons (10-15 mL) or 8.6-17.2 mg tablets once daily, preferably at bedtime 1, 2
• Maximum dose: 3 teaspoons (15 mL) or equivalent tablets twice daily 2
• Commercially available tablets: Most contain 8-9 mg of sennosides per tablet 1

Children 6-12 years:

• Initial dose: 1-1.5 teaspoons (5-7.5 mL) once daily 2
• Maximum dose: 1.5 teaspoons (7.5 mL) twice daily 2

Children 2-6 years:

• Initial dose: 0.5-0.75 teaspoons (2.5-3.75 mL) once daily 2
• Maximum dose: 0.75 teaspoon (3.75 mL) once daily 2

Children <2 years:

• Medical consultation required 2

Mechanism of Action

Senna (sennosides) works as a stimulant laxative by:

• Stimulating prostaglandin E2 production
• Promoting chloride ion secretion
• Increasing colonic peristalsis
• Altering luminal water content 1, 3

Over 90% of sennosides and their metabolites are excreted in feces 1

Treatment Duration

• No specific maximum treatment duration is established in guidelines 1
• Dosing should be titrated based on symptom response and side effects 1
• Clinical trials have typically used 4-week treatment periods 1
• For chronic idiopathic constipation, senna may be used as a first-line agent with ongoing monitoring for efficacy and side effects 1

Potential Side Effects and Precautions

Common Side Effects:

• Abdominal pain/cramping (especially at higher doses)
• Diarrhea
• Nausea 1, 4

Important Precautions:

1. Dose reduction: 83% of participants in clinical trials reduced their daily dose due to side effects 1
2. Pregnancy: Not generally recommended during pregnancy due to potential weak genotoxic effects observed in animal studies (though evidence is controversial) 1
3. Skin reactions: Rare cases of perineal blistering have been reported, particularly with higher doses (>60mg/day) and prolonged stool-to-skin contact 4
4. Children: Generally safe in children when used appropriately, but caregivers should be advised to change diapers frequently to avoid skin irritation 4

Clinical Application

• Senna is an attractive first-line option for chronic idiopathic constipation due to its efficacy, impact on quality of life, over-the-counter availability, and low cost 1
• For postoperative constipation, senna alone is recommended as first-line therapy, particularly in patients receiving opioids for pain management 3
• In patients with refractory constipation not responding to senna, consider other agents such as lubiprostone 1

Limitations of Evidence

• Only a single, small RCT from Japan supports senna's efficacy in chronic idiopathic constipation 1
• The dose used in clinical trials (1g daily) is higher than typically used in clinical practice 1
• Long-term effectiveness and safety data are limited 1

Remember to administer senna at bedtime for optimal effect and to start with lower doses, titrating up as needed to minimize adverse effects 3, 2.