# Cascara (Rhamnus purshiana) *Cascara sagrada, sacred bark; *Rhamnus purshiana* DC.; *Rhamnus alnifolius* Pursh; *Frangula purshiana* (DC.) A. Gray; in pharmacy *Rhamni purshianae cortex** **Known today as.** The dried bark of *Rhamnus purshiana*, a small buckthorn tree of the family Rhamnaceae found, King’s Dispensatory says, from the Rocky Mountains west to the Pacific and north into British America, with leaves three to five inches long, small white flowers in close clusters, and a black fruit the size of a large pea. The bark comes in quills or curved pieces, brownish-grey outside, yellowish within, without odour and bitter. The European Medicines Agency’s assessment report explains why it is dried before use: the fresh bark holds anthrones that cause vomiting, which drying oxidises into forms free of that effect. Kind: Plant Poisoning: The anthranoid purgatives (https://thethinkingpress.org/materia-medica/poisons/anthranoid) > **Caution.** A stimulant laxative, for short use only: long use may impair the bowel’s function and bring dependence, loss of water and potassium, and a harmless darkening of the bowel lining. Not in pregnancy or breast-feeding, because of experimental evidence of genotoxic risk from some anthranoids and their passage into milk; not under twelve; not with bowel obstruction, appendicitis, inflammatory bowel disease, unexplained abdominal pain, or severe dehydration. Potassium loss can strengthen cardiac glycosides and interact with antiarrhythmics, and diuretics, corticosteroids, and liquorice add to it. The urine may turn yellow or red-brown. LiverTox finds it generally safe in recommended doses for a short time, but records several cases of liver injury, a few severe, after longer use of high doses; chronic overdose of anthranoid medicines may cause toxic hepatitis. ## What was it used for? A laxative. LiverTox records that ‘cascara sagrada’ is Spanish for “sacred bark” and that it was used for centuries by Native Americans as a laxative. King’s Dispensatory says it was highly recommended on its introduction as a certain remedy for habitual constipation, a claim further trial had substantially sustained, though it acted best “where a tonic to the intestines is required,” producing semifluid stools “without irritating or griping.” ## What does modern science say? The European Medicines Agency’s herbal committee accepts the bark on clinical evidence, as ‘well-established use,’ for short-term use in occasional constipation (monograph of 2020). Its assessment report requires at least 8 per cent of hydroxyanthracene glycosides, most of them cascarosides, the anthrone glycosides credited with the laxative action. It also found no clinical studies of cascara alone or in combination in a representative population with constipation, the laxative effect resting “mainly” on pharmacological data, expert opinion, and clinical experience. ## Pharmacognosy and toxicology - **cascarosides**: most of the hydroxyanthracene glycosides, at least 8 per cent required; the anthrone glycosides credited with the laxative action **Mechanism.** A stimulant laxative of the anthranoid kind; the fresh bark holds emetic anthrones, which drying oxidises. **Standing.** European Union herbal monograph (2020): well-established use, for short-term use in occasional constipation. ## What lore surrounds it? King’s records that Mr James G. Steele reckoned the country producing the tree to extend over a thousand miles, and that the California buckthorn probably supplied part of the cascara sagrada of commerce. ## What did the older authorities say? **King’s American Dispensatory (1898).** “Cascara sagrada was discovered by an Eclectic physician, Dr. J. H. Bundy,” its virtues first extolled in Detroit in 1877; Parke, Davis & Co. introduced the fluid extract to the profession, and to their efforts, King’s judged, was due the drug’s widespread celebrity. The bark had long been known in domestic practice among western people as a mild cathartic. ## Sources - Felter, H. W., & Lloyd, J. U. (1898). *King’s American Dispensatory*, vol. 2, “Rhamnus Purshiana.” Internet Archive, kingsamericandis02kinguoft. - European Medicines Agency, Committee on Herbal Medicinal Products. *European Union herbal monograph on Rhamni purshianae cortex (Cascara)*. EMA/HMPC/726270/2016, 6 May 2020. - European Medicines Agency, Committee on Herbal Medicinal Products. *Assessment report on Rhamni purshianae cortex*. EMA/HMPC/909434/2019, 6 May 2020. - LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, “Cascara.” National Institute of Diabetes and Digestive and Kidney Diseases, updated 2017. NCBI Bookshelf. - European Medicines Agency, Committee on Herbal Medicinal Products. *European Union herbal monograph on Rhamni purshianae cortex (Cascara)*. EMA/HMPC/726270/2016, 6 May 2020. - European Medicines Agency, Committee on Herbal Medicinal Products. *Assessment report on Rhamni purshianae cortex*. EMA/HMPC/909434/2019, 6 May 2020. - LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, “Cascara.” National Institute of Diabetes and Digestive and Kidney Diseases, updated 2017. NCBI Bookshelf. --- *Cascara.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-16. The Thinking Press. https://thethinkingpress.org/materia-medica/cascara Historical description, not medical advice.