Senna

Senna alexandrina · Cassia angustifolia · Sennosides

Snapshot

Indications	Contraindications
Chronic constipation¹ Opioid-induced constipation^{2, 3} Colonoscopy bowel preparation⁴ Constipation in older adults^{1, 5–7} Pre-dialysis kidney disease constipation⁸	Intestinal obstruction⁹ Pregnancy and lactation⁹ Inflammatory bowel disease⁹ Children under 12⁹

Senna is the leaf and pod of Senna alexandrina (Cassia angustifolia), whose sennosides act as a stimulant laxative that drives colonic contractions¹⁰. People take it for constipation, including chronic idiopathic constipation, opioid-induced constipation², and bowel cleansing before colonoscopy⁴. The European Union herbal monograph covers short-term use in occasional constipation⁹.

A placebo-controlled trial in chronic constipation found senna improved overall symptoms and bowel movement frequency, comparable to magnesium oxide¹. A meta-analysis found senna bowel preparation matched other regimens for cleanliness, with better tolerance. In a 2000 randomized study of colonoscopy patients, a purified senna extract increased colonic cell proliferation and shortened crypts.¹¹ The authors raised a possible cancer-promoting effect of chronic use, which the study did not test¹¹. Products listing senna number 747, sold as capsules, liquids, tablets, teas, and powders; see Form comparison.

Per the European Union herbal monograph, intestinal obstruction is a contraindication because abdominal pain, nausea, and vomiting can signal ileus⁹. The monograph asks patients taking cardiac glycosides, diuretics, or corticosteroids to consult a doctor first, because potassium loss compounds⁹.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

49 sources, 41 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources