What are the guidelines for using Senna (sennosides) for constipation?

Guidelines for Using Senna (Sennosides) for Constipation

Senna is recommended as a first-line agent for chronic idiopathic constipation, with a conditional recommendation and low certainty of evidence according to the 2023 American Gastroenterological Association guidelines. 1

Dosing Recommendations

• Initial dosing:

  • Adults and children ≥12 years: 2-3 teaspoons (10-15 mL) or 8.6-17.2 mg tablets once daily, preferably at bedtime 2, 3
  • Children 6-12 years: 1-1½ teaspoons (5-7.5 mL) once daily 3
  • Children 2-6 years: ½-¾ teaspoons (2.5-3.75 mL) once daily 3
  • Children <2 years: Consult a doctor 3

• Maximum dosing:

  • Adults and children ≥12 years: 3 teaspoons (15 mL) or up to 4 tablets twice daily 2, 3
  • Children 6-12 years: 1½ teaspoons (7.5 mL) twice daily 3
  • Children 2-6 years: ¾ teaspoon (3.75 mL) once daily 3

Duration of Treatment

• Clinical trials evaluated senna for 4 weeks, but longer-term use is likely appropriate 1
• The 2023 AGA guidelines suggest that while trials were conducted for 4 weeks, longer-term use is probably appropriate, though more data are needed to better understand tolerance and side effects 1
• No evidence of tolerance development was found in pediatric populations 4

Mechanism of Action

Senna (anthranoid plant compound) works through:

• Hydrolysis by colonic bacteria glycosidases to yield active molecules 1
• Stimulation of prostaglandin E2 production and chloride ion secretion 2
• Both motor and secretory effects on the colon 1
• Over 90% of sennosides and metabolites are excreted in feces 2

Side Effects and Monitoring

• Common side effects:

  • Abdominal pain/cramping (especially at higher doses) 1, 2
  • Diarrhea 2
  • Nausea 2

• Special considerations:

  • Start at a lower dose and increase if no response 1
  • The dose evaluated in trials is higher than commonly used doses in practice 1
  • Antibiotics may potentially decrease efficacy by affecting colonic bacteria that produce active metabolites 2
  • Not generally recommended during pregnancy due to potential weak genotoxic effects observed in animal studies 2
  • Perineal blistering is a rare side effect, primarily associated with higher doses (60mg/day) and prolonged stool-to-skin contact 4

Clinical Pearls

• Best taken in the evening or at bedtime, with the aim of producing a normal stool the next morning 1
• Wide variation in clinical effectiveness exists between patients 1
• Stimulating effect may be too strong for overtly weak or debilitated patients 1
• In advanced cancer patients, senna is classified as a stimulant laxative generally preferred in advanced disease 1
• For refractory constipation, consider adding or switching to other agents:
  • Bisacodyl or sodium picosulfate (strong recommendation, moderate evidence) 1
  • For chronic idiopathic constipation not responding to OTC agents, consider prescription medications like linaclotide, plecanatide, or prucalopride (strong recommendations, moderate evidence) 1

Senna is an attractive option due to its efficacy, positive impact on quality of life, over-the-counter availability, and low cost 2.