Skip to main content


Scientific Name(s): Rhamnus purshiana DC
Common Name(s): Bitter bark, Buckthorn, Cascara sagrada, Cascararinde, Chittem bark, Cortex rhamni purshianae, Purshiana bark, Rhamnus, Sacred bark

Medically reviewed by Last updated on Nov 10, 2022.

Clinical Overview


Clinical studies of cascara have focused on its laxative effects, although cascara is no longer considered safe or effective for this use. Attention has shifted to cascara's constituent emodin and its possible therapeutic applications in the treatment of various conditions, based on animal and in vitro data.


Cascara sagrada nonprescription laxative products were declared no longer safe or effective by the US Food and Drug Administration (FDA) in 2002 due to a lack of supporting evidence. Typical doses of cascara are 1 g of the bark, 2 to 6 mL as a fluid extract, or 100 to 300 mg of dried bark extract.


Cascara is contraindicated in children younger than 10 years; for ileus due to any origin; and for inflammatory diseases of the colon, including ulcerative colitis, irritable bowel syndrome (IBS), and Crohn disease.


Avoid use. Emmenagogue and abortifacient effects have been documented. Anthranoid metabolites may also be excreted in breast milk.


None well documented.

Adverse Reactions

Side effects include abdominal cramping and discomfort. Extended use may cause chronic diarrhea and consequent electrolyte imbalance. Cases of benign and reversible melanosis coli have been reported.


Overdose of anthraquinone laxatives results in intestinal pain and severe diarrhea, with consequent electrolyte imbalance and dehydration. No causal relationship between long-term use of cascara and colorectal cancer has been established.

Scientific Family

  • Rhamnaceae


The official Cascara sagrada is the dried bark of the typically small- to medium-sized R. purshiana wild deciduous tree found in North America (eg, California, Oregon, Washington, Idaho, Montana) and as far north as Southeast British Columbia. The tree grows up to 18 m in height and has thin, elliptical to ovate-oblong, acutely pointed leaves. The greenish flowers are arranged in umbellate cymes, and the fruit is purplish-black, broadly obovoid, and 8 mm in length. Commercial bark is flattened or transversely curved, longitudinally ridged, and brownish to red-brown in color. The bark has gray or white lichen patches and occasional moss attachments.(Leung 1980, Osol 1955, USDA 2010, WHO 2002) A synonym is Frangula purshiana (D.C.) A. Gray ex J.C. Cooper.


In traditional medicine, cascara was used as a laxative by American Indians and immigrants to America. R. purshiana itself was not described officially until 1805 and was not introduced into medicine until 1877. The berries of the European counterpart (European buckthorn, Rhamnus frangula) were described in the London Pharmacopoeia of 1650. In 2002, the FDA issued a final rule stating Cascara sagrada as a nonprescription laxative ingredient is no longer generally recognized as safe and effective.(Evans 1989, FDA 2002, Leung 1980, WHO 2002)


The active laxative constituents of cascara include at least 6% to 9% anthracene derivatives, which exist as normal O-glycosides and C-glycosides. The 4 primary glycosides or cascarosides A, B, C, and D contain both O- and C-glycosidin linkages that are chemically designated as the C-10 isomers of the 8-O-beta-D-glucopyranosides of aloin and chrysophanol. A number of dianthrones are also present, including emodin, chrysophanol, and the heterodianthrones, as well as palmidin A, B, and C.

The free anthraquinones are likely formed in the leaves and stored in the bark, mainly as C-glycosides, with older bark containing the highest concentration. Although not a commercially viable source, R. purshiana cell suspension cultures produce anthracene derivatives.

Cascara juice also contains other nonlaxative compounds such as rhamnol (cinchol, cupreol, quebrachol); linoleic, myristic, and syringic acids; resins, fat, starch, and glucose; and malic and tannic acid. The dried seeds contain 7% to 25% protein, 13% to 57% oil, and 1% to 2% ash. Recently, six anthraquinone diglucosides from Cascara sagrada bark were isolated by high-performance countercurrent chromatography.(Rho 2020)

Only the dried bark of the trunk or branches of the Cascara sagrada plant is used since the fresh bark contains free anthrone. The free anthrone can cause severe vomiting and is therefore destroyed by treatment of the bark with heat and aeration or by aging it for at least a year.(Santucci 2021)

Analysis and quantification of cascara's chemical constituents have been reported, and techniques for the production of emodin derivatives have been published.(Alaerts 2007, Bisset 1994, Coskun 1989, Duke 1985, Evans 1989, FDA 2002, Koyama 2008, Leung 1980, Lu 2006, Tan 2006, Wei 1992)

Uses and Pharmacology


On November 5, 2002, the FDA ruled that Cascara sagrada nonprescription laxative products were no longer considered safe and effective.(FDA 2002) Systematic reviews published in 2001 reported the use of cascara and other laxatives in randomized controlled trials demonstrating improvement in bowel movement frequency, consistency, and symptoms, with no clear evidence regarding any superiority of various treatments.(Petticrew 2001) A 2010 systematic review found no clinically important results from randomized controlled trials regarding the safe or effective use of cascara in adults with chronic idiopathic constipation.(Mueller-Lissner 2010) Studies conducted in elderly populations show that the majority of patients using long-term laxative preparations, including cascara, were able to discontinue laxative use when a fiber supplement was added.(Khaja 2005, Mihaylov 2008, Petticrew 2001)

As with other stimulant laxatives (eg, aloe, senna), anthraglycosides are responsible for the cathartic properties of cascara. Cascarosides A and B are the major principles that act on the large intestine to induce peristalsis and evacuation. More specifically, anthraglycosides produce an active secretion of water and electrolytes within the lumen of the small intestine and inhibit their absorption from the large intestine, causing an increase in bowel content volume and strengthening of intestinal dilatation pressure to stimulate peristalsis.(Evans 1989, Leung 1980, WHO 2002) The emodin glycoside is also responsible for laxative action, first requiring metabolism to the active aglycone by intestinal flora and possibly increasing the excitability of the smooth muscles of the intestinal wall.(Srinivas 2007, Zhang 2005) For more detailed information, refer to the Emodin monograph.


On November 5, 2002, the FDA ruled that nonprescription Cascara sagrada stimulant laxative products were no longer generally recognized as safe or effective due to a lack of supporting evidence.(FDA 2002, Santucci 2021) Use in children younger than 10 years is contraindicated.(WHO 2002) Commercial cascara preparations include crude preparations, extracts, and essential oil.(Leung 1980) Typical doses of cascara are 1 g of the bark, 2 to 6 mL as a fluid extract, or 100 to 300 mg of dried bark extract.(Duke 1985) The laxative effect is generally not observed for 6 to 8 hours after administration. Because of the risk of electrolyte imbalance, use should be limited to less than 2 weeks.(WHO 2002)

Pregnancy / Lactation

Avoid use. Emmenagogue and abortifacient effects have been documented.Brinker 1998, Ernst 2002, Newall 1996 Anthranoid metabolites may be excreted in breast milk.WHO 2002


Case reports are lacking. Long-term cascara use may lead to potassium deficiency, which can potentiate the effects of cardiac glycosides, antiarrhythmics, and corticosteroids.Abebe 2003, Vogel 2005 Interference with the absorption of other drugs is possible with anthranoid-containing plants, including senna and cascara.Fugh-Berman 2000, WHO 2002

Adverse Reactions

Side effects such as abdominal cramping and discomfort. Rare side effects from long term usage can include nephrotoxicity, cardiotoxicity, hepatotoxicity, hypokalemia, muscle weakness, cachexia and melanosis coli.(Santucci 2021)

Extended or habitual use of cascara should be avoided because it can cause chronic diarrhea and weakness due to excessive potassium loss. Long-term use can also cause melanosis coli (melanin pigmentation of the colon mucous membranes), a benign and reversible injury of the colonic epithelial cells caused by anthraquinones. In one case report, a patient developing melanosis coli was asymptomatic; however, symptoms of diarrhea, fatigue, and weight loss have been reported in other cases.(Bechara 2016, Bisset 1994, Duke 1985, Grilo 2014, Kew 2013)

A case report exists of intrahepatic cholestasis and consequent portal hypertension related to cascara use. However, it was unclear if this event was due to the cascara preparation or to the adulterants.(Nadir 2000) Freshly prepared cascara product contains anthrones, which can result in severe vomiting and intestinal cramping when consumed; therefore, the bark should be stored for at least 1 year before use or processed by heating or aeration to eliminate the anthrone principles.(de Witte 1990)


Overdose of anthraquinone laxatives results in intestinal pain and severe diarrhea, with consequent electrolyte imbalance and dehydration. Treatment is symptomatic, with special attention given to potassium and other electrolyte levels, especially in elderly patients and children.WHO 2002

No causal relationship between long-term use of cascara and colorectal cancer has been established.WHO 2002 In a rat colon carcinogenesis model, cascara did not increase the incidence of aberrant crypt foci or tumors.Borrelli 2001 In one study, samples of herbal preparations were evaluated for heavy metal contamination (cadmium, mercury, and lead), with low levels reported for cascara.Caldas 2004

Index Terms

  • Frangula purshiana (D.C.) A. Gray ex J.C. Cooper



This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

Abebe W. An overview of herbal supplement utilization with particular emphasis on possible interactions with dental drugs and oral manifestations. J Dent Hyg. 2003;77(1):37-46.12704968
Alaerts G, Matthijs N, Smeyers-Verbeke J, Vander Heyden Y. Chromatographic fingerprint development for herbal extracts: a screening and optimization methodology on monolithic columns. J Chromatogr A. 2007;1172(1):1-8.17942105
Bechara R, Marcon N, Streutker CJ. Melanosis coli: a disappearing act. Gastrointest Endosc. 2016;83(6):1296-1298.26555299
Bisset NG, ed. Herbal Drugs and Phytopharmaceuticals. Boca Raton, FL: CRC Press; 1994.
Borrelli F, Mereto E, Capasso F, et al. Effect of bisacodyl and cascara on growth of aberrant crypt foci and malignant tumors in the rat colon. Life Sci. 2001;69(16):1871-1877.11693267
Brinker FJ. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications; 1998.
Caldas ED, Machado LL. Cadmium, mercury and lead in medicinal herbs in Brazil. Food Chem Toxicol. 2004;42(4):599-603.15019183
Cortex Rhamni Purshianae. In: WHO Monographs on Selected Medicinal Plants. Vol. 2. Geneva, Switzerland: World Health Organization; 2002.
Coskun M. The quantitative determination of anthraderivatives in Rhamnus species growing in South and East Anatolia (Turkey). Part 2. Int J Crude Drug Res. 1989;27(3):167-170.
de Witte P, Lemli L. The metabolism of anthranoid laxatives. Hepatogastroenterology. 1990;37(6):601-605.2289777
Duke JA. Handbook of Medicinal Herbs. Boca Raton, FL: CRC Press; 1985.
Ernst E. Herbal medicinal products during pregnancy: are they safe? BJOG. 2002;109(3):227-235.11950176
Evans WC. Trease and Evans' Pharmacognosy. 13th ed. London, England: Bailliére Tindall; 1989.
Food and Drug Administration, HHS. Status of certain additional over-the-counter drug category II and III active ingredients. Final rule. Fed Regist. 2002;67(90):31125-31127.12001972
Frangula purshiana. USDA, NRCS. 2007. The PLANTS Database (, January 2010). National Plant Data Team, Greensboro, NC 27401-4901 USA. Accessed January 2010.
Fugh-Berman A. Herb-drug interactions [published correction appears in Lancet. 2000;355(9208):1020]. Lancet. 2000;355(9198):134-138.10675182
Grilo I, Torres-Gómez J, Gómez-Regife L. Atypical melanosis coli resembling the appearance of cheetah skin. Endoscopy. 2014;46(suppl 1):E437-E438.25314182
Kew ST, Chakravarthi S. Images in clinical medicine: Melanosis coli. N Engl J Med. 2013;368(24):2303.23758235
Khaja M, Thakur CS, Bharathan T, Baccash E, Goldenberg G. 'Fiber 7' supplement as an alternative to laxatives in a nursing home. Gerodontology. 2005;22(2):106-108.15934353
Koyama J, Nisino Y, Morita I, Kobayashi N, Osakai T, Tokuda H. Correlation between reduction potentials and inhibitions of Epstein-Barr virus activation by anthraquinone derivatives. Bioorg Med Chem Lett. 2008;18(14):4106-4109.18556196
Leung AY. Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics. New York, NY: Wiley; 1980.
Lu HM, Ni WD, Liang YZ, Man RL. Supercritical CO2 extraction of emodin and physcion from Polygonum cuspidatum and subsequent isolation by semipreparative chromatography. J Sep Sci. 2006;29(14):2136-2142.17069242
Mihaylov S, Stark C, McColl E, et al. Stepped treatment of older adults on laxatives. The STOOL trial. Health Technol Assess. 2008;12(13):iii-iv, ix-139.18462572
Mueller-Lissner SA, Wald A. Constipation in adults. BMJ Clin Evid. 2010;2010. pii: 0413.21418672
Nadir A, Reddy D, Van Thiel DH. Cascara sagrada-induced intrahepatic cholestasis causing portal hypertension: case report and review of herbal hepatotoxicity. Am J Gastroenterol. 2000;95(12):3634-3637.11151906
Newall CA, Anderson LA, Phillipson JD, eds. Herbal Medicines: A Guide for Health-Care Professionals. London, England: Pharmaceutical Press; 1996.
Osol A, Farrar GE, eds. The Dispensatory of the United States of America. 25th ed. Philadelphia, PA: JB Lippincott; 1955.
Petticrew M, Rodgers M, Booth A. Effectiveness of laxatives in adults. Qual Health Care. 2001;10(4):268-273.11743157
Rho T, Kil HW, Seo YJ, Shin KJ, Wang D, Yoon KD. Isolation of six anthraquinone diglucosides from cascara sagrada bark by high-performance countercurrent chromatography. J Sep Sci. 2020;43(21):4036-4046. doi:10.1002/jssc.20200059732876395
Santucci NR, Chogle A, Leiby A, et al. Non-pharmacologic approach to pediatric constipation. Complement Ther Med. 2021;59:102711. doi:10.1016/j.ctim.2021.10271133737146
Srinivas G, Babykutty S, Sathiadevan PP, Srinivas P. Molecular mechanism of emodin action: transition from laxative ingredient to an antitumor agent. Med Res Rev. 2007;27(5):591-608.17019678
Tan JH, Zhang QX, Huang ZS, et al. Synthesis, DNA binding and cytotoxicity of new pyrazole emodin derivatives. Eur J Med Chem. 2006;41(9):1041-1047.16716458
Vogel JH, Bolling SF, Costello RB, et al; American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents (Writing Committee to Develop an Expert Consensus Document on Complementary and Integrative Medicine). Integrating complementary medicine into cardiovascular medicine. A report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents (Writing Committee to Develop an Expert Consensus Document on Complementary and Integrative Medicine). J Am Coll Cardiol. 2005;46(1):184-221.15992662
Wei B-L, Lin C-N, Won S-J. Nakahalene and cytotoxic principles of Formosan Rhamnus species. J Nat Prod. 1992;55(7):967-969.
Zhang HQ, Zhou CH, Wu YQ. Effect of emodin on small intestinal peristalsis of mice and relevant mechanism. World J Gastroenterol. 2005;11(20):3147-3150.15918207

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.