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Herb library · Herb · Senna alexandrina (Cassia senna, C. angustifolia)

Senna

A stimulant laxative made from the leaves and pods of an African and Indian shrub, sold over the counter in teas and tablets. It works for short-term constipation, and it is meant for a week or less: long-term use brings its own problems.

Serious warning

NIH LiverTox reports rare cases of liver injury from senna taken in high doses for longer than recommended, including a woman who developed acute liver failure after drinking large amounts of senna tea for years. The related plant coffee senna (Cassia occidentalis) has caused severe poisoning in children.

Traditional use

Grown in Egypt, Sudan, Arabia and India (Alexandrian and Tinnevelly senna), and used for centuries as a laxative. It is an ingredient in many over-the-counter laxatives and in some teas sold for purging and weight loss. EU regulators accept it for short-term use in occasional constipation, and the pods for clearing the bowel before a medical examination.

Traditional energetics

What studies show

  • Established

    Occasional constipation, short term: the European Medicines Agency's herbal committee calls the data on its effects coherent and accepts it on well-established use. Most trials tested senna combined with fiber, which worked at least as well as comparisons such as lactulose; there is no recent trial of senna on its own.

  • Established

    Clearing the bowel before a colonoscopy or X-ray: 23 trials of high single doses gave consistent results. Standard preparations were slightly more effective, but senna was better tolerated, with less vomiting and more cramping.

  • Insufficient

    Irritable bowel syndrome: the one study of a senna combination product could not show a benefit.

Be careful of

Cautions

  • AmountFor short-term use only. EU products should not be taken for more than one week; MedlinePlus says not to take it for more than a week without talking to your doctor. Using it longer can leave the bowel dependent on laxatives.
  • NoteSide effects include stomach cramps and pain, diarrhea, nausea, allergic itching and rash, and brown or reddish urine. Long-term use can darken the lining of the colon and upset the body's water and salt balance. Stop and call a doctor if you have rectal bleeding.
  • ConditionDo not use it with a bowel blockage or narrowing, appendicitis, Crohn's disease or ulcerative colitis, unexplained belly pain, or severe dehydration. People with kidney problems should watch for salt imbalance. Older adults should not usually take it over a long period.
  • InteractionLoss of potassium from overuse can strengthen the effect of heart drugs such as digoxin and interfere with rhythm drugs; diuretics, corticosteroids and licorice root add to the potassium loss. Some senna products should be taken 2 hours apart from other medicines, and not with mineral oil.
  • PregnancyEU monographs say not to use it while pregnant or breastfeeding (its active substances pass into breast milk in small amounts), or in children under 12.
  • Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.

From the old books

What herbals and dispensaries of the past printed. History, in their words.

“A nursing infant may be purged by the milk of the mother who has taken senna, and so susceptible are some persons to its action, that its odor is said to induce a cathartic action.”
Harvey Wickes Felter and John Uri Lloyd, King's American Dispensatory (1905), vol. 2, p. 1749. See the page of King's American Dispensatory, vol. 2, p. 1749 (opens in a new tab) · Read the full passage from King's American Dispensatory, vol. 2, p. 1749

Sources

  1. Senna leaf - summary for the public (EMA/697536/2018) (opens in a new tab) · EMA · read September 25, 2026
  2. European Union herbal monograph on Senna alexandrina Mill. (Cassia senna L.; Cassia angustifolia Vahl), folium, Rev. 1 (EMA/HMPC/625849/2015) (opens in a new tab) · EMA · read September 25, 2026
  3. Assessment report on Senna alexandrina Mill. (Cassia senna L.; Cassia angustifolia Vahl), folium and fructus, Rev. 1 (EMA/HMPC/228759/2016) (opens in a new tab) · EMA · read September 25, 2026
  4. Senna: MedlinePlus Drug Information (opens in a new tab) · MedlinePlus · read September 25, 2026
  5. Senna - LiverTox: Clinical and Research Information on Drug-Induced Liver Injury (opens in a new tab) · NIH · read September 25, 2026

Reviewed September 25, 2026.