From the Guidelines
The recommended dose of senna for adults with constipation is 1 g by mouth daily for a short period, as evidenced by the single RCT published to date 1. However, it is notable that most commercially available senna products contain 8–9 mg per tablet, and the dose used in the trial is higher than that typically used in clinical practice.
- Key considerations for senna dosing include:
- Starting with a low dose to minimize side effects like abdominal pain, cramping, or diarrhea
- Using the medication for a short period (less than 1 week) to avoid dependence, electrolyte imbalances, and reduced bowel function
- Drinking plenty of water when taking senna
- Discontinuing use if severe abdominal pain or diarrhea occurs
- The combination of efficacy, impact on quality of life, availability over-the-counter, and low cost makes senna an attractive first-line option for individuals with chronic idiopathic constipation, despite limitations in the available evidence 1.
- Rigorous dose-ranging data with senna are currently not available, and long-term safety studies in humans are lacking, which raises concerns about potential adverse events 1.
- Sennosides are not recommended in pregnant women due to potential weak genotoxic effects in animals, although the supporting evidence is controversial 1.
From the FDA Drug Label
PRINCIPAL DISPLAY PANEL - 237 mL Bottle Label NDC 39328-020-08 Senna SyrupNatural VegetableLaxative 8.8mg/5 mL PRINCIPAL DISPLAY PANEL - 5 mL Cup Label Delivers 5 mL NDC 39328-120-05 Senna Syrup 8.8 mg/5 mL PRINCIPAL DISPLAY PANEL - 15 mL Cup Label Delivers 15 mL NDC 39328-220-15 Senna Syrup 26.4 mg/15 mL
The dose for senna is 8.8 mg/5 mL as stated in the labels 2 and 2, and 26.4 mg/15 mL as stated in label 2.
- The available doses are:
- 8.8 mg per 5 mL
- 26.4 mg per 15 mL No standard dose is specified in the provided labels.
From the Research
Dose for Senna
- The dose of Senna can vary depending on the individual and the condition being treated.
- According to a study published in the Journal of pediatric surgery 3, patients who developed blisters had higher doses of 60mg/day, with a range of 12-100mg/day.
- The study found that the doses of Senna were not significantly different in patients who presented minor side effects such as abdominal cramping, vomiting, or diarrhea, with a median dose of 15mg/day and a range of 4.4-150mg/day.
- Another study published in the Journal of pediatric gastroenterology and nutrition 4 used a dose of 2 mg/kg/day of sennosides for 2 days for colonoscopy preparation in children.
- A study published in Health science reports 5 used a combination of low-volume polyethylene glycol and senna for bowel preparation, but the exact dose of senna was not specified.
Side Effects and Efficacy
- The study published in the Journal of pediatric surgery 3 found that Senna-induced dermatitis is rare, but may occur when patients need a higher dose.
- The study published in Digestive diseases (Basel, Switzerland) 6 found that the efficacy, safety, and adverse effect profile of 1-day bowel preparation with PEG-B regimen was similar to 3-day sennosides regimen.
- The study published in Cancer treatment reviews 7 found that polyethylene glycol was significantly more effective than sennosides in treating opioid-induced constipation.
Comparison with Other Laxatives
- The study published in the Journal of pediatric gastroenterology and nutrition 4 found that there were no significant differences in the efficacy of bowel preparation among high-volume polyethylene glycol, low-volume polyethylene glycol combined with bisacodyl, and sennosides.
- The study published in Health science reports 5 found that the quality of colon preparation was equally efficient in the high-volume PEG group and the low-volume PEG plus senna group.