Recommended Dosage of Senna for Constipation
For adults with constipation, the recommended dose of senna is 2-3 teaspoons (10-15 mL) once daily at bedtime, with a maximum dosage of 3 teaspoons (15 mL) twice daily. 1
Adult Dosing Guidelines
- For initial treatment of constipation, start with 2-3 teaspoons (10-15 mL) of senna syrup once daily, preferably at bedtime 1
- Maximum daily dose should not exceed 3 teaspoons (15 mL) twice daily 1
- For tablet formulations, typical starting dose is 8.6-17.2 mg daily (equivalent to 1-2 standard tablets) 2
- In palliative care settings, senna may be dosed at 2-3 tablets twice to three times daily for patients with severe constipation 2
Pediatric Dosing
- Children 6-12 years: 1 to 1½ teaspoons (5-7.5 mL) once daily, maximum 1½ teaspoons twice daily 1
- Children 2-6 years: ½ to ¾ teaspoons (2.5-3.75 mL) once daily, maximum ¾ teaspoon once daily 1
- Children under 2 years: Consult a doctor before use 1
Mechanism of Action and Efficacy
- Senna contains anthranoid plant compounds that are hydrolyzed by colonic bacteria to yield active molecules 2
- It has both motor and secretory effects on the colon, stimulating peristalsis 2
- Best taken in the evening or at bedtime to produce a normal stool the next morning 2
- In clinical trials, senna significantly increased complete spontaneous bowel movements compared to placebo 2
Clinical Considerations
- Senna is classified as a stimulant laxative and is considered one of the most physiological non-fiber laxatives 3
- It is recommended for short-term use (4 weeks or less) or as rescue therapy 2
- While long-term use is probably appropriate in some cases, data on tolerance and side effects with extended use are limited 2
- Start at a lower dose and increase if there is inadequate response 2
- Senna may be more effective than polyethylene glycol in certain patient populations with constipation related to hypomotility 4
Side Effects and Precautions
- Common side effects include abdominal pain, cramping, and diarrhea, particularly at higher doses 2
- Perineal blistering has been reported in rare cases, usually related to high doses or prolonged skin contact with stool 5
- In comparative studies, senna has shown more side effects than some other laxatives like lactulose 6
- Stimulant laxatives like senna may be too strong for overtly weak or debilitated patients 2
- When used in palliative care, senna alone may be more effective than senna combined with docusate 7
Practical Administration Tips
- Shake liquid formulations well before using 1
- Taking senna with adequate fluid intake is recommended 3
- For patients with cancer-related constipation, senna may be increased to 2-3 tablets BID-TID with the goal of one non-forced bowel movement every 1-2 days 2
- Consider adding other laxatives if constipation persists despite optimal senna dosing 2