Supplement

Senna

Senna is a plant-based laxative whose natural compounds, called anthraquinone glycosides, stimulate the nerves in the colon wall, which speeds up muscle movement and draws fluid into the gut. People mostly look at it for constipation, and trials found symptoms improved, including in older adults and in cancer patients taking opioids. Those studies were very small, just 30 people across two trials, so the evidence for constipation is limited, though other research found it made the intestines move more.

Sources: PMID 8234438; PMID 9436336

Updated 30 September 2026
How we grade
10 studies cited

Best evidence: Grade A
Conditions studied: 6
Outcomes: 10
Graded outcomes: 1220

Evidence by condition

Strong
Moderate
Limited
Very limited

6 conditions

Digestive Health

Digestive Health: outcomes studied for Senna
Grade	Outcome	Effect	Size	Studies	People
	Intestinal Motility Large Increase	Improves (the measure goes up)	Large effect	8 studies	165 people
Studies that measured intestinal motility Standardized senna in the management of constipation in the puerperium: A clinical trialS Afr Med J · PMID 6996138 The use of senna with docusate for postoperative constipation after pelvic reconstructive surgery: a randomized, double-blind, placebo-controlled trialAm J Obstet Gynecol · PMID 20207340 A volunteer model for the comparison of laxatives in opioid-related constipationJ Pain Symptom Manage · PMID 8935140 Comparison of the effect of drugs upon some commonly used measures of bowel transit timeBr J Clin Pharmacol · PMID 728318 Comparative study of two bowel preparation regimens for colonoscopy: senna tablets vs sodium phosphate solutionWorld J Gastroenterol · PMID 17006995 Half doses of PEG-ES and senna vs. high-dose senna for bowel cleansing before colonoscopy: a randomized, investigator-blinded trialAm J Gastroenterol · PMID 19844199 The bowel cleansing for colonoscopy. A randomized trial comparing three methodsAnn Ital Chir · PMID 17147088 Senna vs polyethylene glycol for mechanical preparation the evening before elective colonic or rectal resection: a multicenter controlled trial. French Association for Surgical ResearchArch Surg · PMID 10323423
	Constipation Signs and Symptoms Large Improvement	Improves (the measure goes down)	Large effect	2 studies	31 people
Studies that measured constipation signs and symptoms Efficacy of senna versus lactulose in terminal cancer patients treated with opioidsJ Pain Symptom Manage · PMID 9436336 Safety and efficacy of a bulk laxative containing senna versus lactulose in the treatment of chronic constipation in geriatric patientsPharmacology · PMID 8234438

Irritable Bowel Syndrome (IBS)

Irritable Bowel Syndrome (IBS): outcomes studied for Senna
Grade	Outcome	Effect	Size	Studies	People
	Constipation Signs and Symptoms Large Improvement	Improves (the measure goes down)	Large effect	2 studies	519 people
Studies that measured constipation signs and symptoms Efficacy of senna versus lactulose in terminal cancer patients treated with opioidsJ Pain Symptom Manage · PMID 9436336 Safety and efficacy of a bulk laxative containing senna versus lactulose in the treatment of chronic constipation in geriatric patientsPharmacology · PMID 8234438
	Intestinal Motility	Improves (the measure goes up)		8 studies	519 people
Studies that measured intestinal motility Standardized senna in the management of constipation in the puerperium: A clinical trialS Afr Med J · PMID 6996138 The use of senna with docusate for postoperative constipation after pelvic reconstructive surgery: a randomized, double-blind, placebo-controlled trialAm J Obstet Gynecol · PMID 20207340 A volunteer model for the comparison of laxatives in opioid-related constipationJ Pain Symptom Manage · PMID 8935140 Comparison of the effect of drugs upon some commonly used measures of bowel transit timeBr J Clin Pharmacol · PMID 728318 Comparative study of two bowel preparation regimens for colonoscopy: senna tablets vs sodium phosphate solutionWorld J Gastroenterol · PMID 17006995 Half doses of PEG-ES and senna vs. high-dose senna for bowel cleansing before colonoscopy: a randomized, investigator-blinded trialAm J Gastroenterol · PMID 19844199 The bowel cleansing for colonoscopy. A randomized trial comparing three methodsAnn Ital Chir · PMID 17147088 Senna vs polyethylene glycol for mechanical preparation the evening before elective colonic or rectal resection: a multicenter controlled trial. French Association for Surgical ResearchArch Surg · PMID 10323423

General Gut Health

Constipation Signs and Symptoms: improves
Intestinal Motility: improves

General Gut Health: outcomes studied for Senna
Grade	Outcome	Effect	Size	Studies	People
	Constipation Signs and Symptoms Large Improvement	Improves (the measure goes down)	Large effect	2 studies	8 people
Studies that measured constipation signs and symptoms Efficacy of senna versus lactulose in terminal cancer patients treated with opioidsJ Pain Symptom Manage · PMID 9436336 Safety and efficacy of a bulk laxative containing senna versus lactulose in the treatment of chronic constipation in geriatric patientsPharmacology · PMID 8234438
	Intestinal Motility	Improves (the measure goes up)		8 studies	665 people
Studies that measured intestinal motility Standardized senna in the management of constipation in the puerperium: A clinical trialS Afr Med J · PMID 6996138 The use of senna with docusate for postoperative constipation after pelvic reconstructive surgery: a randomized, double-blind, placebo-controlled trialAm J Obstet Gynecol · PMID 20207340 A volunteer model for the comparison of laxatives in opioid-related constipationJ Pain Symptom Manage · PMID 8935140 Comparison of the effect of drugs upon some commonly used measures of bowel transit timeBr J Clin Pharmacol · PMID 728318 Comparative study of two bowel preparation regimens for colonoscopy: senna tablets vs sodium phosphate solutionWorld J Gastroenterol · PMID 17006995 Half doses of PEG-ES and senna vs. high-dose senna for bowel cleansing before colonoscopy: a randomized, investigator-blinded trialAm J Gastroenterol · PMID 19844199 The bowel cleansing for colonoscopy. A randomized trial comparing three methodsAnn Ital Chir · PMID 17147088 Senna vs polyethylene glycol for mechanical preparation the evening before elective colonic or rectal resection: a multicenter controlled trial. French Association for Surgical ResearchArch Surg · PMID 10323423

Constipation

Constipation Signs and Symptoms: improves
Intestinal Motility: improves

Constipation: outcomes studied for Senna
Grade	Outcome	Effect	Size	Studies	People
	Constipation Signs and Symptoms Large Improvement	Improves (the measure goes down)	Large effect	2 studies	30 people
Studies that measured constipation signs and symptoms Efficacy of senna versus lactulose in terminal cancer patients treated with opioidsJ Pain Symptom Manage · PMID 9436336 Safety and efficacy of a bulk laxative containing senna versus lactulose in the treatment of chronic constipation in geriatric patientsPharmacology · PMID 8234438
	Intestinal Motility	Improves (the measure goes up)		8 studies	30 people
Studies that measured intestinal motility Standardized senna in the management of constipation in the puerperium: A clinical trialS Afr Med J · PMID 6996138 The use of senna with docusate for postoperative constipation after pelvic reconstructive surgery: a randomized, double-blind, placebo-controlled trialAm J Obstet Gynecol · PMID 20207340 A volunteer model for the comparison of laxatives in opioid-related constipationJ Pain Symptom Manage · PMID 8935140 Comparison of the effect of drugs upon some commonly used measures of bowel transit timeBr J Clin Pharmacol · PMID 728318 Comparative study of two bowel preparation regimens for colonoscopy: senna tablets vs sodium phosphate solutionWorld J Gastroenterol · PMID 17006995 Half doses of PEG-ES and senna vs. high-dose senna for bowel cleansing before colonoscopy: a randomized, investigator-blinded trialAm J Gastroenterol · PMID 19844199 The bowel cleansing for colonoscopy. A randomized trial comparing three methodsAnn Ital Chir · PMID 17147088 Senna vs polyethylene glycol for mechanical preparation the evening before elective colonic or rectal resection: a multicenter controlled trial. French Association for Surgical ResearchArch Surg · PMID 10323423

Bowel Cleansing

Intestinal Motility: improves

Bowel Cleansing: outcomes studied for Senna
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Intestinal Motility	Improves (the measure goes up)		8 studies	569 people
Studies that measured intestinal motility Standardized senna in the management of constipation in the puerperium: A clinical trialS Afr Med J · PMID 6996138 The use of senna with docusate for postoperative constipation after pelvic reconstructive surgery: a randomized, double-blind, placebo-controlled trialAm J Obstet Gynecol · PMID 20207340 A volunteer model for the comparison of laxatives in opioid-related constipationJ Pain Symptom Manage · PMID 8935140 Comparison of the effect of drugs upon some commonly used measures of bowel transit timeBr J Clin Pharmacol · PMID 728318 Comparative study of two bowel preparation regimens for colonoscopy: senna tablets vs sodium phosphate solutionWorld J Gastroenterol · PMID 17006995 Half doses of PEG-ES and senna vs. high-dose senna for bowel cleansing before colonoscopy: a randomized, investigator-blinded trialAm J Gastroenterol · PMID 19844199 The bowel cleansing for colonoscopy. A randomized trial comparing three methodsAnn Ital Chir · PMID 17147088 Senna vs polyethylene glycol for mechanical preparation the evening before elective colonic or rectal resection: a multicenter controlled trial. French Association for Surgical ResearchArch Surg · PMID 10323423

General Cancer Care and Prevention

Constipation Signs and Symptoms: improves

General Cancer Care and Prevention: outcomes studied for Senna
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Constipation Signs and Symptoms	Improves (the measure goes down)		2 studies	91 people
Studies that measured constipation signs and symptoms Efficacy of senna versus lactulose in terminal cancer patients treated with opioidsJ Pain Symptom Manage · PMID 9436336 Safety and efficacy of a bulk laxative containing senna versus lactulose in the treatment of chronic constipation in geriatric patientsPharmacology · PMID 8234438

Key findings

Intestinal MotilityDigestive HealthImproves (the measure goes up)
Constipation Signs and SymptomsDigestive HealthImproves (the measure goes down)

Shop the evidence-backed picks

Third-party tested Senna products, in the forms the graded studies used where we can match them.

Grade A

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Studies cited

10 studies from PubMed

Efficacy of senna versus lactulose in terminal cancer patients treated with opioidsJ Pain Symptom Manage · PMID 9436336
Standardized senna in the management of constipation in the puerperium: A clinical trialS Afr Med J · PMID 6996138
The use of senna with docusate for postoperative constipation after pelvic reconstructive surgery: a randomized, double-blind, placebo-controlled trialAm J Obstet Gynecol · PMID 20207340
A volunteer model for the comparison of laxatives in opioid-related constipationJ Pain Symptom Manage · PMID 8935140
Comparison of the effect of drugs upon some commonly used measures of bowel transit timeBr J Clin Pharmacol · PMID 728318
Comparative study of two bowel preparation regimens for colonoscopy: senna tablets vs sodium phosphate solutionWorld J Gastroenterol · PMID 17006995
Half doses of PEG-ES and senna vs. high-dose senna for bowel cleansing before colonoscopy: a randomized, investigator-blinded trialAm J Gastroenterol · PMID 19844199
The bowel cleansing for colonoscopy. A randomized trial comparing three methodsAnn Ital Chir · PMID 17147088
Senna vs polyethylene glycol for mechanical preparation the evening before elective colonic or rectal resection: a multicenter controlled trial. French Association for Surgical ResearchArch Surg · PMID 10323423
Safety and efficacy of a bulk laxative containing senna versus lactulose in the treatment of chronic constipation in geriatric patientsPharmacology · PMID 8234438