Cascara sagrada

What Is Cascara Sagrada?

Cascara sagrada is primarily used for constipation.

The aged bark is exceptionally bitter — which stimulates the vagus nerve, liver, and digestive organs. As bile acids and pancreatic secretions begin moving in the gastrointestinal tract, it triggers the gastric mucosa to expand and contract. This is important to help foods move through the digestive tract.

Some of the active compounds in the herb work by irritating the digestive mucosa — causing them to writhe and contract.

This herb needs to be used carefully — high doses can be very uncomfortable and result in serious harm.

What Is Cascara Sagrada Used For?

Cascara sagrada is mainly used as a lower bowel tonic for treating constipation.

Traditional Uses

Traditional use of cascara sagrada included: intestinal tonic, dyspepsia, constipation, digestion related headaches, to loosen stool for conditions such as haemorrhoids, rheumatism, biliary catarrh with jaundice, and chronic liver diseases ^{18Reference 18Bone · 2003A Clinical Guide to Blending Liquid Herbs}.

Native Americans used cascara sagrada as a cathartic ^{18Reference 18Bone · 2003A Clinical Guide to Blending Liquid Herbs}.

Botanical Information

The Rhamnaceae (buckthorn) family of plants contains 55 genera, and 950 different species. This family has a wide distribution, especially throughout the tropics.

Harvesting, Collection & Preparation

The bark of cascara sagrada is harvested in spring and early summer. During this time it’s easily peeled from the tree. It’s then dried in the shade. Aged bark (3 years) is generally the preferred product, as the emetic effects lessen over this time and is much less likely to cause issues with griping and emesis ^{17Reference 17A Modern Herbal · 1931Buckthorn (Californian). https://www.botanical.com/botanical/mgmh/b/buckth80.htmlView study →}.

Phytochemistry

The laxative action of cascara is driven by its hydroxyanthracene derivatives (anthranoids), which make up around 8% of the dried bark by mass ^{2Reference 2EFSA Panel on Food Additives et al. · 2018ReviewSafety of hydroxyanthracene derivatives for use in food — pharmacopoeial standard and genotoxicity reviewView study →}. The signature compounds are the cascarosides — C-glycosylated anthrones unique to this group of plants — which account for roughly 60–70% of the total glycosides; the European Pharmacopoeia requires no less than 8% total hydroxyanthracenes, of which at least 60% are cascarosides (calculated as cascaroside A) ^{2Reference 2EFSA Panel on Food Additives et al. · 2018ReviewSafety of hydroxyanthracene derivatives for use in food — pharmacopoeial standard and genotoxicity reviewView study →}. The cascarosides occur as the diastereomeric pairs A/B (derived from aloins/barbaloin) and C/D (derived from chrysophanol) ^{2Reference 2EFSA Panel on Food Additives et al. · 2018ReviewSafety of hydroxyanthracene derivatives for use in food — pharmacopoeial standard and genotoxicity reviewView study →}.

Behind these sit the aglycone anthraquinones emodin, aloe-emodin and chrysophanol, along with their anthrone glycosides. Emodin in particular is the constituent most studied for cascara’s anticancer activity. Astringent tannins are also present and partly offset the bowel-stimulating effect.

Constituent Summary

Figures are share of the dried bark (total hydroxyanthracenes) or share of total glycosides, per the European Pharmacopoeia standard; the remaining aglycones and tannins are qualitative as published figures vary widely with bark age and aging time ^{2Reference 2EFSA Panel on Food Additives et al. · 2018ReviewSafety of hydroxyanthracene derivatives for use in food — pharmacopoeial standard and genotoxicity reviewView study →}.

Pharmacology & Research

Cascara sagrada is one of the better-characterised stimulant (anthranoid) laxatives, but its evidence base is lopsided: the laxative action itself rests on well-mapped pharmacology and pharmacopoeial standardisation rather than modern controlled trials, while the largest published body of primary research on cascara’s constituents concerns the anthraquinone emodin in cancer cell lines — work that is almost entirely in vitro and does not reflect how the bark is used. No placebo-controlled RCT of cascara sagrada as a laxative has been registered or published, and the U.S. FDA reclassified it as not generally recognised as safe and effective for over-the-counter use in 2002 for want of submitted data ^{3Reference 3Food et al. · 2002Status of certain additional over-the-counter drug category II and III active ingredients (cascara sagrada reclassified as not GRASE)View study →}. The same hydroxyanthracene constituents that drive the laxative effect also carry a genotoxicity signal that led the EU to restrict them in food in 2021 ^{2,4Reference 2EFSA Panel on Food Additives et al. · 2018ReviewSafety of hydroxyanthracene derivatives for use in food — pharmacopoeial standard and genotoxicity reviewView study →Reference 4Silva Souza et al. · 2025In vitroPhytotoxicity and cytogenotoxic effects of extracts from the medicinal bark of Rhamnus purshiana DC. — in vitroView study →}. Because constituent profile varies widely with bark age and species, results from isolated emodin or from related Rhamnus/Frangula species transfer poorly to the aged bark preparations actually taken.

0. Evidence by indication

Support is an experimental score I’m building — a composite weighted by study type (human > animal > in vitro > review) and study volume. It’s a beta: a fast way to rank strength of evidence at a glance, not a validated metric, and I’ll keep honing the formula over time. Each indication name links down to its write-up.

Indication	Support	Rests on
Laxative	███████░░░ 71%	Established anthranoid pharmacology + pharmacopoeial standardisation and centuries of human use; no modern cascara-specific RCT, and the FDA withdrew OTC recognition for lack of data 1,2,3Reference 1Lombardi et al. · 2022Meta-analysisAnthraquinone laxatives use and colorectal cancer: systematic review and meta-analysis of observational studiesView study →Reference 2EFSA Panel on Food Additives et al. · 2018ReviewSafety of hydroxyanthracene derivatives for use in food — pharmacopoeial standard and genotoxicity reviewView study →Reference 3Food et al. · 2002Status of certain additional over-the-counter drug category II and III active ingredients (cascara sagrada reclassified as not GRASE)View study →.
Anticancer	███░░░░░░░ 30%	Emodin and related anthraquinones in cancer cell lines only; low oral bioavailability, prep mismatch, and the same molecules are genotoxic 4,5,7,15Reference 4Silva Souza et al. · 2025In vitroPhytotoxicity and cytogenotoxic effects of extracts from the medicinal bark of Rhamnus purshiana DC. — in vitroView study →Reference 5Demarque et al. · 2018In vitroCytotoxicity of structurally diverse anthranoids and correlation with mechanism of action and side effects — in vitroView study →Reference 7Xing et al. · 2015In vitroAntitumor effects and mechanism of novel emodin rhamnoside derivatives against human cancer cells in vitroView study →Reference 15Tinti et al. · 2023In vitroHydroxyanthracene derivatives cytotoxicity: a differential evaluation between single molecule and whole plant extract — in vitroView study →.
Antiviral	██░░░░░░░░ 24%	Two in vitro studies (envelope inactivation; EBV suppression); no cellular-uptake or in vivo confirmation 6,16Reference 6Sydiskis et al. · 1991In vitroInactivation of enveloped viruses by anthraquinones extracted from plants — in vitroView study →Reference 16Koyama et al. · 2001In vitroInhibitory effects of anthraquinones and bianthraquinones on Epstein-Barr virus activation — in vitroView study →.

1. Laxative

Cascara’s laxative effect is the one indication with a coherent, replicated mechanism. The bark’s C-glycosylated anthrones — the cascarosides, which account for roughly 60–70% of its total glycosides and are the marker the European Pharmacopoeia standardises to (not less than 8% total hydroxyanthracenes) — pass largely unabsorbed through the small intestine and are cleaved by colonic bacteria to active aglycones such as aloe-emodin anthrone ^{2,13,14Reference 2EFSA Panel on Food Additives et al. · 2018ReviewSafety of hydroxyanthracene derivatives for use in food — pharmacopoeial standard and genotoxicity reviewView study →Reference 13Nezi et al. · 2025Untargeted metabolomics for profiling of cascara, senna, rhubarb, and frangula metabolitesView study →Reference 14Rho et al. · 2020Isolation of six anthraquinone diglucosides from cascara sagrada bark by high-performance countercurrent chromatographyView study →}. These act locally in the large bowel, increasing propulsive motility and net fluid-and-electrolyte secretion through prostaglandin- and nitric-oxide–mediated pathways ^{1Reference 1Lombardi et al. · 2022Meta-analysisAnthraquinone laxatives use and colorectal cancer: systematic review and meta-analysis of observational studiesView study →}. The action is real and pharmacopoeially recognised (WHO, ESCOP, Commission E), but the human evidence is old and cascara-specific: modern trials benchmark other bowel regimens, and a 2022 meta-analysis of anthraquinone laxatives treats the class as a whole rather than cascara individually ^{1Reference 1Lombardi et al. · 2022Meta-analysisAnthraquinone laxatives use and colorectal cancer: systematic review and meta-analysis of observational studiesView study →}. In 2002 the FDA moved cascara from the OTC “generally recognised as safe and effective” category to Category II/III — a regulatory judgement about missing submitted data, not a finding that it fails to work ^{3Reference 3Food et al. · 2002Status of certain additional over-the-counter drug category II and III active ingredients (cascara sagrada reclassified as not GRASE)View study →}.

Gap: no placebo-controlled RCT of cascara sagrada itself for constipation; efficacy is inferred from anthranoid-class pharmacology and traditional use, and the standardised dose is defined chemically rather than clinically.

2. Anticancer

The bark’s most-studied single molecule, the anthraquinone emodin, is structurally similar to the anthracycline chemotherapeutics and shows anti-proliferative, pro-apoptotic (mitochondrial/intrinsic pathway) and anti-angiogenic activity across many cancer cell lines ^{7Reference 7Xing et al. · 2015In vitroAntitumor effects and mechanism of novel emodin rhamnoside derivatives against human cancer cells in vitroView study →}. Semi-synthetic emodin glycoside derivatives improve on the parent molecule’s potency and bioavailability in vitro ^{7Reference 7Xing et al. · 2015In vitroAntitumor effects and mechanism of novel emodin rhamnoside derivatives against human cancer cells in vitroView study →}. But almost all of this work is cell-line based, emodin’s oral bioavailability is low, and — the decisive caveat — this is not how cascara is used: the bark is taken as a short-course laxative, not as a source of isolated emodin. A 2018 structure–activity analysis places the anthranoids’ cytotoxicity on the same axis as their gut-irritant and genotoxic effects, so “anticancer” and “adverse” are not cleanly separable properties ^{5Reference 5Demarque et al. · 2018In vitroCytotoxicity of structurally diverse anthranoids and correlation with mechanism of action and side effects — in vitroView study →}. Whole-extract studies further show that isolated-molecule cytotoxicity does not straightforwardly predict what the crude bark does ^{15Reference 15Tinti et al. · 2023In vitroHydroxyanthracene derivatives cytotoxicity: a differential evaluation between single molecule and whole plant extract — in vitroView study →}.

Gap: no in vivo tumour models with the bark itself and no clinical data; the activity belongs to an isolated constituent at exposures unrelated to laxative dosing, and the responsible molecules are genotoxic ^{4Reference 4Silva Souza et al. · 2025In vitroPhytotoxicity and cytogenotoxic effects of extracts from the medicinal bark of Rhamnus purshiana DC. — in vitroView study →}.

3. Antiviral

A 1991 study reported that anthraquinones extracted from cascara and other plants — including emodin and aloe-emodin — inactivated enveloped viruses (herpes simplex, pseudorabies, influenza) in vitro by interacting directly with the viral envelope and blocking adsorption, while leaving non-enveloped viruses unaffected ^{6Reference 6Sydiskis et al. · 1991In vitroInactivation of enveloped viruses by anthraquinones extracted from plants — in vitroView study →}. A separate 2001 report found anthraquinones suppressed Epstein–Barr virus early-antigen activation in a cell assay ^{16Reference 16Koyama et al. · 2001In vitroInhibitory effects of anthraquinones and bianthraquinones on Epstein-Barr virus activation — in vitroView study →}. Both are direct-contact in vitro findings with no confirmation that ingested cascara reaches relevant tissue concentrations.

Gap: two isolated in vitro reports, decades old, with no pharmacokinetic bridge to systemic antiviral exposure and no animal or human data.

Mechanisms

Mechanism	Drives	Key compounds
Colonic bacterial hydrolysis of cascarosides → active anthrone aglycones	laxative	aloe-emodin, emodin
↑ propulsive motility + net fluid/electrolyte secretion (prostaglandin, nitric-oxide mediated)	laxative	anthrone aglycones
DNA intercalation, mitochondrial (intrinsic) apoptosis, NF-κB ↓	anticancer (in vitro)	emodin, aloe-emodin
Direct binding to and inactivation of the viral envelope	antiviral (in vitro)	emodin, aloe-emodin
Topoisomerase interference / genotoxicity (efficacy and safety share the same target)	anticancer signal, safety concern	emodin, aloe-emodin, chrysophanol

Clinical trials

No registered clinical trials of cascara sagrada for constipation or any other indication were identified (ClinicalTrials.gov hits for “cascara” refer to coffee-cherry pulp or unrelated acronym trials); the efficacy base is pharmacopoeial and mechanistic, and the constituent research is preclinical.

Completed	Planned	Terminated	Preclinical
0	0	0	~40

Last checked: July 2026.

Dosage

Regulatory guidance frames cascara’s dose by hydroxyanthracene content, not raw bark weight, because bark potency varies with aging — and use is short-term only.

Indication	Preparation	Dose	Est. dried-herb equivalent	Source
Constipation (laxative)	Standardised extract, hydroxyanthracenes as cascaroside A	20–30 mg hydroxyanthracenes/day (pharmacopoeial daily dose)	~0.25–0.4 g dried bark (assuming bark ≈ 8% hydroxyanthracenes)	2Reference 2EFSA Panel on Food Additives et al. · 2018ReviewSafety of hydroxyanthracene derivatives for use in food — pharmacopoeial standard and genotoxicity reviewView study →

The dried-herb equivalent is back-converted from the marker dose on the stated assumption that dried bark ≈ 8% hydroxyanthracenes (European Pharmacopoeia minimum) — a guide only, not a recommendation. Cascara is dosed by hydroxyanthracene content precisely because bark potency varies with aging.

Traditional Dosage

System	Preparation	Dose
Western herbal	Liquid extract 1:2	20–50 mL/week (short courses)
Western herbal	Dried aged bark (≥1 yr, decoction/infusion)	~0.3–1 g as a single evening dose

Safety

Cascara sagrada is a stimulant (anthranoid) laxative for short-term use only — repeated or prolonged use causes electrolyte loss (notably potassium depletion), laxative dependence, and atonic colon, and pharmacopoeial and regulatory bodies limit continuous use to about one to two weeks ^{2Reference 2EFSA Panel on Food Additives et al. · 2018ReviewSafety of hydroxyanthracene derivatives for use in food — pharmacopoeial standard and genotoxicity reviewView study →}. Its hydroxyanthracene constituents carry a genotoxicity signal: EFSA concluded in 2018 that aloe-emodin, emodin, and structurally related anthranoids raise safety concern, and the EU subsequently restricted these compounds in food ^{2,4Reference 2EFSA Panel on Food Additives et al. · 2018ReviewSafety of hydroxyanthracene derivatives for use in food — pharmacopoeial standard and genotoxicity reviewView study →Reference 4Silva Souza et al. · 2025In vitroPhytotoxicity and cytogenotoxic effects of extracts from the medicinal bark of Rhamnus purshiana DC. — in vitroView study →}. Chronic use pigments the colonic mucosa (melanosis coli), a benign, reversible marker of anthranoid exposure that is nonetheless associated with a higher detection rate of colorectal adenoma ^{11,12Reference 11Abu Baker et al. · 2018ReviewMelanosis coli: a helpful contrast effect or a harmful pigmentation? — reviewView study →Reference 12Katsumata et al. · 2022ObservationalSevere grade of melanosis coli is associated with a higher detection rate of colorectal adenoma — observationalView study →}; a 2022 meta-analysis of anthraquinone laxatives found a modest association with colorectal cancer risk that could not be separated from confounding by constipation itself ^{1Reference 1Lombardi et al. · 2022Meta-analysisAnthraquinone laxatives use and colorectal cancer: systematic review and meta-analysis of observational studiesView study →}. Cascara sagrada has caused idiosyncratic cholestatic hepatitis, portal hypertension, and acute liver injury in case reports ^{8,9,10Reference 8Nadir et al. · 2000Case reportCascara sagrada-induced intrahepatic cholestasis causing portal hypertension: case report and review of herbal hepatotoxicityView study →Reference 9Nakasone et al. · 2015A case of cholangiocarcinoma identified incidentally after acute liver injury due to cascara sagradaView study →Reference 10Jacobsen et al. · 2009Case reportToxic hepatitis following consumption of the herbal medicinal product cascara sagrada — case reportView study →}, and the U.S. FDA withdrew its over-the-counter “generally recognised as safe and effective” status in 2002 ^{3Reference 3Food et al. · 2002Status of certain additional over-the-counter drug category II and III active ingredients (cascara sagrada reclassified as not GRASE)View study →}. Potassium loss can potentiate cardiac glycosides (e.g. digoxin) and interact with antiarrhythmics, diuretics, and corticosteroids — a class-level pharmacological caution for stimulant laxatives.

Pregnancy & lactation

Avoid. Cascara sagrada is contraindicated in pregnancy: stimulant anthranoid laxatives are traditionally avoided for their potential to stimulate the uterus and cause reflex bowel activity, and the genotoxicity concern attached to its hydroxyanthracene constituents reinforces this ^{2Reference 2EFSA Panel on Food Additives et al. · 2018ReviewSafety of hydroxyanthracene derivatives for use in food — pharmacopoeial standard and genotoxicity reviewView study →}. Anthranoid metabolites can pass into breast milk, so it is generally not recommended during lactation. These are precautionary, class-based positions — cascara sagrada itself has not been formally studied in pregnancy or lactation.

Clinical Applications

Cascara sagrada is mainly used for constipation and as a tonic for poor bowel motility.

Synergy

Suggested synergy with boldo for digestive complaints such as constipation, flatulence, and abdominal fullness ^{18Reference 18Bone · 2003A Clinical Guide to Blending Liquid Herbs}.

Combine with rhubarb, boldo, and gentian for dyspepsia ^{18Reference 18Bone · 2003A Clinical Guide to Blending Liquid Herbs}.

References

1. Lombardi, N., Crescioli, G., Bettiol, A., et al. (2022). Anthraquinone laxatives use and colorectal cancer: systematic review and meta-analysis of observational studies. Phytotherapy Research. https://pubmed.ncbi.nlm.nih.gov/35040201/
2. EFSA Panel on Food Additives and Nutrient Sources (ANS). (2018). Safety of hydroxyanthracene derivatives for use in food — pharmacopoeial standard and genotoxicity review. EFSA Journal. https://pubmed.ncbi.nlm.nih.gov/32625659/
3. Food and Drug Administration, HHS. (2002). Status of certain additional over-the-counter drug category II and III active ingredients (cascara sagrada reclassified as not GRASE). Federal Register. https://pubmed.ncbi.nlm.nih.gov/12001972/
4. Silva Souza, K., et al. (2025). Phytotoxicity and cytogenotoxic effects of extracts from the medicinal bark of Rhamnus purshiana DC. — in vitro. Journal of Toxicology and Environmental Health, Part A. https://pubmed.ncbi.nlm.nih.gov/39964315/
5. Demarque, D. P., et al. (2018). Cytotoxicity of structurally diverse anthranoids and correlation with mechanism of action and side effects — in vitro. Journal of Pharmacy & Pharmaceutical Sciences. https://pubmed.ncbi.nlm.nih.gov/30321134/
6. Sydiskis, R. J., Owen, D. G., Lohr, J. L., Rosler, K. H., & Blomster, R. N. (1991). Inactivation of enveloped viruses by anthraquinones extracted from plants — in vitro. Antimicrobial Agents and Chemotherapy. https://pubmed.ncbi.nlm.nih.gov/1810179/
7. Xing, J. Y., Song, G. P., Deng, J. P., et al. (2015). Antitumor effects and mechanism of novel emodin rhamnoside derivatives against human cancer cells in vitro. PLOS ONE. https://pubmed.ncbi.nlm.nih.gov/26682731/
8. Nadir, A., Reddy, D., & Van Thiel, D. H. (2000). Cascara sagrada-induced intrahepatic cholestasis causing portal hypertension: case report and review of herbal hepatotoxicity. American Journal of Gastroenterology. https://pubmed.ncbi.nlm.nih.gov/11151906/
9. Nakasone, E. S., & Tokeshi, J. (2015). A case of cholangiocarcinoma identified incidentally after acute liver injury due to cascara sagrada. Hawai’i Journal of Medicine & Public Health. https://pubmed.ncbi.nlm.nih.gov/26114074/
10. Jacobsen, C., Semb, S., & Kromann-Andersen, H. (2009). Toxic hepatitis following consumption of the herbal medicinal product cascara sagrada — case report. Ugeskrift for Laeger. https://pubmed.ncbi.nlm.nih.gov/19925744/
11. Abu Baker, F., et al. (2018). Melanosis coli: a helpful contrast effect or a harmful pigmentation? — review. Clinical Medicine Insights: Gastroenterology. https://pubmed.ncbi.nlm.nih.gov/30574001/
12. Katsumata, R., et al. (2022). Severe grade of melanosis coli is associated with a higher detection rate of colorectal adenoma — observational. Journal of Clinical Biochemistry and Nutrition. https://pubmed.ncbi.nlm.nih.gov/36213792/
13. Nezi, P., et al. (2025). Untargeted metabolomics for profiling of cascara, senna, rhubarb, and frangula metabolites. Metabolites. https://pubmed.ncbi.nlm.nih.gov/41441021/
14. Rho, T., et al. (2020). Isolation of six anthraquinone diglucosides from cascara sagrada bark by high-performance countercurrent chromatography. Journal of Separation Science. https://pubmed.ncbi.nlm.nih.gov/32876395/
15. Tinti, L., et al. (2023). Hydroxyanthracene derivatives cytotoxicity: a differential evaluation between single molecule and whole plant extract — in vitro. Frontiers in Plant Science. https://pubmed.ncbi.nlm.nih.gov/37113593/
16. Koyama, J., Morita, I., Tagahara, K., & Hirai, K. (2001). Inhibitory effects of anthraquinones and bianthraquinones on Epstein-Barr virus activation — in vitro. Cancer Letters. https://pubmed.ncbi.nlm.nih.gov/11448529/
17. A Modern Herbal (1931). Buckthorn (Californian). https://www.botanical.com/botanical/mgmh/b/buckth80.html
18. Bone, K. (2003). A Clinical Guide to Blending Liquid Herbs. Churchill Livingstone.