Senna (Senna alexandrina): Evidence, Dosage & Uses

Tropical African Shrub · Laxative Herb

Botanical Overview

Senna is a subshrub or shrub of tropical Africa, 1 to 1.5 m tall, with pinnate leaves made of an even number of leaflets. It bears many yellow flowers, and its fruit is a flat, kidney-shaped, parchment-like pod that splits into two valves and releases 5 to 10 seeds.

HabitShrub, 1–1.5 m

LeavesPinnate, even leaflets

FlowersYellow, about 3 cm

FruitFlat kidney-shaped pod

Taxonomic Classification

Taxonomy & Identification

Latin Name: Senna alexandrina Mill. (accepted name Cassia senna L.; synonyms Cassia acutifolia (Delile) Batka and Cassia angustifolia Vahl)
Family: Fabaceae (subfamily Caesalpinioideae)
Common Names: Senna, Alexandrian Senna, Khartoum Senna, Indian Senna, Tinnevelly Senna, Séné
Parts Used: Leaflets and pods (fruit)
Regulatory Status: French Pharmacopoeia, list A (leaflet and fruit); EMA-evaluated herbal substance ²

Ethnobotany & Traditional Use

History & Tradition

Arab physicians were already prescribing senna in the 9th century. Alexandria was the historic export port for the senna sold under its name, while the Indian senna reached the market from the pre-desert regions of Arabia.

Both the leaflets and the pods are used, prepared as a cold maceration, an infusion or a decoction, and today most often as tablets standardized to their sennoside content.

Modern work has defined how sennosides are activated in the colon, tested senna against other laxatives in constipation trials, and examined its safety in long-term use. ²¹⁵¹¹¹²

⚠ Short-Term Use Only

Senna is meant for occasional constipation and for about a week at a time. Longer use risks dependence and loss of potassium. ²

Timeline

Arab Medicine

9th Century

Arab physicians begin prescribing senna as a purgative.

Trade Through Alexandria

Historic Trade

Alexandria becomes the export port for senna, which takes its name from the city.

Pharmacopoeia Listing

Official Status

The leaflet and the fruit are listed in the French Pharmacopoeia, list A.

European Dose Revision

2016

The EU assessment of leaf and pod revises the daily range to 10–30 mg of hydroxyanthracene derivatives. ¹

The Key Compounds

Sennosides & Rhein Anthrone — Deep Dive

The dianthrone glycosides, their active metabolite and the mucilage behind senna's laxative effect.

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Sennosides A–F

Dianthrone glycosides making up more than 3% of the drug. They are not absorbed in the upper gut and arrive in the colon intact. ¹

🧬

Rhein Anthrone

The active metabolite. Colonic bacteria convert sennosides to sennidins and then to rhein anthrone, which acts on the colon wall. ¹²

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Rhein, Emodin & Aloe-Emodin

The free anthraquinones of the drug. Less than 4% of an oral dose of the metabolite reaches the bloodstream, and rhein glucuronides tint the urine yellow or red-brown. ¹

💧

Mucilages

Making up 2 to 3% of the drug, they swell in water into a gel that helps hold water in the colon and soften the stool.

Pharmaceutical Preparations

Parts Used & Available Forms

The leaflets and the pods are used, as simple teas or standardized tablets.

Leaflet

The dried leaflets, listed in the French Pharmacopoeia (list A).

Leaf

Pod

The dried kidney-shaped fruit; the pulp is the traditional part.

Fruit

Herbal Tea

Infusion of the dried leaflets or pods, taken in the evening.

Infusion

Cold Maceration & Decoction

Traditional preparations of the pods steeped in cold water or simmered.

Traditional

Mother Tincture

Teinture-mère of the leaflet.

Liquid Extract

Standardized Tablets

Tablets and extracts calibrated to their hydroxyanthracene content, expressed as sennoside B.

Standardized Extract

Clinical Dosimetry

Dosages

Senna is taken once a day at night, at the smallest dose that gives a soft stool, and for only a few days at a time.

Form	Dose	Frequency	Context	Notes
Standardized Tablet or Extract	10–30 mg hydroxyanthracene derivatives (as sennoside B)	Once daily, at night	Occasional constipation	Use the smallest dose that gives a comfortable soft stool, for no more than one week. ¹²
Leaflet or Pod Tea (Infusion)	0.5–2 g of dried drug	Once daily, in the evening	Occasional constipation	A bitter tea; the effect arrives 8 to 12 hours later. ³
Sennoside B	20–30 mg	Per day	General use	Daily total of purified sennoside B. ³
Pods (Traditional)	2–6 pods	Once daily	Occasional constipation	Prepared as a cold maceration, infusion or decoction, in courses of no more than 10 days to protect colon muscle tone.

Phytochemistry

Composition

Dianthrone glycosides carry the laxative activity, supported by anthraquinones, mucilage and flavonoids.

Leaflet & Pod — Primary Constituents

Dianthrone GlycosidesMore than 3%: sennosides A, B, C, D, E and F

Major

AnthraquinonesRhein, emodin and aloe-emodin ¹

Present

Mucilages2 to 3% of the drug

Present

FlavonoidsKaempferol derivatives

Present

Naphthalene GlycosidesGlycosides of tinnevelline and 6-hydroxymusizin

Present

Sennoside Derivatives & Metabolites

SennosidesDimers formed from hydroxyanthracene precursors during drying and during infusion at about 40 °C

Major

SennidinsIntermediate products of bacterial breakdown in the colon ¹

Present

Rhein AnthroneThe active metabolite, formed by colonic bacteria ¹

Present

Rhein GlucuronidesExcreted in urine, where they can tint it yellow or red-brown ²

Present

Aloe-Emodin GlucuronidesFound in serum after leaf intake in rats ¹

Present

Plant Properties — Pharmacodynamics

Twelve pharmacodynamic properties define senna, centered on colonic stimulation, bacterial activation and long-term safety.

12 Properties Stimulant Laxative Colonic Prodrug Clinical Trials

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Stimulant Laxative

A contact laxative that produces a bowel movement about 8 to 12 hours after a dose. ²³

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Colonic Motility

The active anthrones stimulate the movement of the colon wall directly. ²

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Water & Electrolyte Transport

Reduces sodium absorption, increases potassium secretion and draws water into the bowel lumen. ²

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Stool Softening

Mucilages swell into a gel, and together with the sennosides they retain water in the colon.

🦠

Gut-Flora Activation

Works as a prodrug: bacteria in the colon convert sennosides into rhein anthrone. ¹

📍

Minimal Systemic Absorption

About 90% leaves in the stool as polymers, and only 3 to 6% of metabolites appear in urine. ¹²

⏱️

Predictable Onset

Taken at night, it acts the next morning, with no accumulation of rhein in blood after 7 days of use. ²

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Colonic Mucosal Changes

Reversible mucosal hyperplasia in animals at high doses, and a reversible darkening of the colon lining (pseudomelanosis) in long-term use. ¹²

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Genotoxicity Profile

Sennosides, rhein and the pod extract were negative in most tests; aloe-emodin was genotoxic in vitro but not in vivo. ¹²

🛡️

Carcinogenicity Studies

Reviewed in toxicology literature and in a National Toxicology Program study in genetically modified mice. ¹¹¹²¹³

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Liver Safety Signals

Hepatitis and liver failure appear in case reports of heavy use, while a combined cell and animal study found no liver toxicity. ¹⁴¹⁵¹⁶¹⁷¹⁸

⚡

Potassium Depletion

Long-term use lowers potassium, which can magnify the effect of digoxin. ²¹⁹

Clinical Applications

Clinical Indications

Senna is used for occasional constipation, with comparison trials and reviews in adults, children and palliative settings.

🚽

Occasional Constipation

Primary Indication

Short-Term Relief: taken once daily at night for no more than about a week. ²
Placebo-Controlled Trial: a randomized trial compared senna with magnesium oxide in chronic constipation, and both eased symptoms. ⁵
Systematic Review: traditional medical therapies for chronic constipation, senna among them, were reviewed. ⁴

🏥

Opioid & Palliative Care Constipation

Clinical Setting

Palliative Care: laxatives for people receiving palliative care were reviewed in a Cochrane review. ⁶
After Orthopedic Surgery: lubiprostone was compared with senna for opioid-induced constipation. ⁷

🧒

Childhood Constipation

Supervised Use

Stimulant Laxatives: osmotic and stimulant laxatives for children were reviewed in a Cochrane review. ⁸
Anorectal Malformation: senna was compared with polyethylene glycol in affected children. ⁹
Long-Term Use: the safety of prolonged senna in children has been questioned and studied. ¹⁰

🩹

Anal Fissure

Traditional Indication

Soft Stools: senna is used when stools need to be kept soft so that straining is avoided.
Hemorrhoids: use with caution in people with hemorrhoids. ³

Pharmacodynamics

Mode of Action

Senna works only in the colon, where bacteria turn inactive sennosides into the compound that moves the bowel.

🦠

Activation in the Colon

Sennosides pass unabsorbed through the upper gut. Colonic bacteria convert them to sennidins and then to rhein anthrone. ¹²

🌀

Stimulation of Colonic Motility

Rhein anthrone stimulates the muscle of the colon wall and changes how the colon moves water and electrolytes. ²

💦

Sodium, Potassium & Water

Sodium absorption falls, potassium secretion rises and water is drawn into the lumen, which loosens the stool.

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Mucilage Gel

The mucilages swell into gels and colloidal solutions that hold water in the colon and soften the stool.

⏱️

Onset & Elimination

A bowel movement follows after 8 to 12 hours. About 90% of the dose is excreted in the stool as polymers. ²

Clinical Safety

Safety & Interactions

Senna is for short courses only, and it is not for pregnancy, children under 12 or any bowel obstruction.

⚠️

Adverse Effects & Precautions

Cramps & Loose Stools: abdominal pain and diarrhea, especially with overdose or an irritable bowel. ²
Long-Term Use: laxative dependence, water and electrolyte imbalance, albumin or blood in the urine, and a reversible darkening of the colon lining. ²³
Urine Color: harmless yellow or red-brown discoloration.
Liver & Skin: rare hepatitis with heavy use, and diaper-area blistering in young children. ¹⁴¹⁶²⁰

🚫

Contraindications & Interactions

Contraindications: intestinal obstruction or stenosis, appendicitis, Crohn's disease, ulcerative colitis, abdominal pain of unknown cause and severe dehydration. ²
Pregnancy, Lactation & Children: not advised in pregnancy or breastfeeding, nor under 12 years. ²
Drug Interactions: digoxin and other cardiac glycosides, antiarrhythmics, QT-prolonging drugs, diuretics, corticosteroids and licorice root. ²¹⁹
Bowel Preparations: avoid combining with sodium sulfate preparations, and monitor with polyethylene glycol solutions. ³

Clinical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice. Consult a qualified healthcare provider before using senna, particularly if you are pregnant or breastfeeding, take heart medicines or diuretics, have a bowel disease, or have constipation that lasts more than a week.

Common Questions

Frequently Asked Questions

What is senna used for?

Senna (Senna alexandrina) leaflets and pods are used as a stimulant laxative for occasional constipation. Traditionally they are also used to keep stools soft when straining should be avoided, as in an anal fissure.

How long does senna take to work?

A bowel movement usually follows 8 to 12 hours after a dose, which is why senna is taken once a day at night.

What is the usual senna dosage?

For occasional constipation, the adult dose is 10 to 30 mg of hydroxyanthracene derivatives, calculated as sennoside B, taken once daily at night. The right dose is the smallest one that gives a comfortable soft stool. As a tea, about 0.5 to 2 g of dried leaflets or pods is used, and treatment should not run beyond about one week without medical advice.

Is it safe to take senna every day?

Senna is meant for short-term use. Prolonged use can lead to laxative dependence, water and electrolyte imbalance, especially low potassium, and a darkening of the colon lining (pseudomelanosis coli) that usually reverses after stopping. Toxicology reviews have examined cathartic colon, genotoxicity and carcinogenicity, and one concluded that senna is a laxative devoid of carcinogenic effects.

Is senna safe in pregnancy or while breastfeeding?

Senna is not advised in pregnancy or breastfeeding. Some anthranoids, such as emodin and aloe-emodin, have raised genotoxic concerns, and small amounts of the active metabolite rhein pass into breast milk. A 2009 case-control study found no higher rate of congenital abnormalities among women who used senna during pregnancy.

Can senna damage the liver?

Rare case reports link heavy or prolonged senna use to hepatitis and, with abuse, to acute liver failure. A senna extract was not hepatotoxic in a combined cell and animal study. Staying within the labeled dose and duration is the safest course.

Which medicines interact with senna?

Long-term laxative use lowers potassium, which strengthens the effect of digoxin and other cardiac glycosides and interacts with antiarrhythmics. Diuretics, corticosteroids and licorice root add to the potassium loss. Senna should also not be combined with sodium sulfate bowel preparations.

Is senna safe for children?

Herbal senna products are contraindicated under 12 years unless a doctor directs their use. In young children, senna-containing laxatives have caused blistering and skin breakdown in the diaper area. Stimulant laxatives, senna included, are used in childhood constipation under medical supervision.

What are the side effects of senna?

Abdominal cramps and loose stools are the common effects, particularly at higher doses and in people with irritable bowel. Yellow or red-brown urine is harmless. Itching, hives or rash can occur as an allergic reaction.

Sources

Bibliography

↑1. European Medicines Agency (EMA/HMPC). Assessment report on Senna alexandrina Mill. (Cassia senna L.; Cassia angustifolia Vahl), folium and fructus, Revision 1. EMA/HMPC/228759/2016.
Full Text (PDF) →

↑2. European Medicines Agency (EMA/HMPC). European Union herbal monograph on Senna alexandrina Mill. (Cassia senna L.; Cassia angustifolia Vahl), folium, Revision 1.
EMA Herbal Page →

↑3. Natural Medicines. Senna. In: Drugs.com Natural Products Database.
Full Text →

↑4. Ramkumar D, Rao SS. Efficacy and safety of traditional medical therapies for chronic constipation: systematic review. Am J Gastroenterol. 2005.
PubMed: PMID 15784043 →

↑5. Senna versus magnesium oxide for the treatment of chronic constipation: a randomized, placebo-controlled trial. Am J Gastroenterol.
DOI: 10.14309/ajg.0000000000000942 →

↑6. Candy B, et al. Laxatives for the management of constipation in people receiving palliative care. Cochrane Database Syst Rev. 2015.
PubMed: PMID 25967924 →

↑7. Marciniak CM, et al. Lubiprostone vs senna in postoperative orthopedic surgery patients with opioid-induced constipation. World J Gastroenterol. 2014;20(43):16323.
Abstract →

↑8. Gordon M, et al. Osmotic and stimulant laxatives for the management of childhood constipation. Cochrane Database Syst Rev. 2016.
DOI: 10.1002/14651858.CD009118.pub3 →

↑9. Effectiveness of senna vs polyethylene glycol as laxative therapy in children with constipation related to anorectal malformation. J Pediatr Surg. 2016.
Abstract →

↑10. Are senna based laxatives safe when used as long term treatment for constipation in children? J Pediatr Surg. 2018.
PubMed: PMID 29429768 →

↑11. Morales MA, et al. Is senna laxative use associated to cathartic colon, genotoxicity, or carcinogenicity? J Toxicol. 2009;2009:287247.
DOI: 10.1155/2009/287247 →

↑12. Borrelli F, et al. Senna: a laxative devoid of carcinogenic effects. Arch Toxicol. 2006.
DOI: 10.1007/s00204-005-0021-9 →

↑13. Surh I, et al. Toxicology and carcinogenesis study of senna in C3B6.129F1-Trp53 haploinsufficient mice. Toxicol Pathol. 2013;41(5):770–778.
DOI: 10.1177/0192623312464304 →

↑14. Seybold U, et al. Senna-induced hepatitis in a poor metabolizer. Ann Intern Med. 2004.
PubMed: PMID 15492352 →

↑15. Sonmez A, et al. Subacute cholestatic hepatitis likely related to the use of senna for chronic constipation. Acta Gastroenterol Belg. 2005;68(3).
Full Text →

↑16. Vanderperren B, et al. Acute liver failure with renal impairment related to the abuse of senna anthraquinone glycosides. Ann Pharmacother. 2005.
PubMed: PMID 15956233 →

↑17. Vitalone A, et al. Cassia angustifolia extract is not hepatotoxic in an in vitro and in vivo study. Pharmacology. 2011.
PubMed: PMID 21997710 →

↑18. Soyuncu S, et al. Portal vein thrombosis related to Cassia angustifolia. Clin Toxicol (Phila). 2008.
PubMed: PMID 19238740 →

↑19. Wang MT, et al. Exposure to sennoside-digoxin interaction and risk of digoxin toxicity: a population-based nested case-control study. Eur J Heart Fail. 2011.
PubMed: PMID 21803754 →

↑20. Spiller HA, et al. Skin breakdown and blisters from senna-containing laxatives in young children. Ann Pharmacother. 2003.
PubMed: PMID 12708936 →

↑21. Ulbricht C, et al. An evidence-based systematic review of senna (Cassia senna). J Diet Suppl. 2011.
Record →

Additional Sources

Wikiphyto. Séné d'Alexandrie (Cassia senna). Taxonomy, traditional use, composition and traditional posology.
Full Text →