Cascara Sagrada
RhamnaceaeFrangula purshiana
Also known as: Cascara, Sacred Bark, Rhamnus purshiana
clinical_notes Clinical Summary
Cascara Sagrada (Frangula purshiana) is a North American buckthorn whose aged bark contains anthraquinone glycosides (cascarosides) producing a stimulant laxative effect within 8-12 hours.
Historically the dominant OTC laxative in the US until the FDA revoked its GRAS status in 2002.
Use should be strictly short-term (less than 1 week) in adults; contraindicated in pregnancy, lactation, children, and IBD.
Pregnancy Safety
Avoid in pregnancy. FDA removed cascara from OTC laxative status in 2002. Bulk-forming laxatives are preferred alternatives.
Lactation Safety
Contraindicated while breastfeeding. Anthraquinones cross into milk and can induce diarrhea in the infant.
warning Contraindications
- Pregnancy (contraindicated)Theoretical
- Lactation (contraindicated)Clinically Proven
- Children (contraindicated)Clinically Proven
- Inflammatory bowel disease (Crohn's, ulcerative colitis) (contraindicated)Clinically Proven
- Use >1 week / long-term use (contraindicated)Clinically Proven
- Concurrent use of cardiac glycosides (digoxin) or thiazide diuretics (avoid)Theoretical
vital_signs Clinical Profile
Primary Indications
- check_circle short-term constipation
- check_circle occasional constipation
Therapeutic Actions
System Affinities
- check_circle digestive system
- check_circle colon
- check_circle hepatobiliary
labs Active Constituents
cascarosides A, B, C, D
aloin-like anthrones
emodin
chrysophanol
barbaloin
resins
tannins
history_edu Traditional Use
No TCM data available for this herb yet.
Traditional Uses Across Healing Systems
While many herbs lack controlled clinical trials, centuries of traditional practice across cultures provide valuable insight into their therapeutic applications.
Pacific Northwest First Nations used the aged bark as a laxative for constipation.
Chinook Jargon name 'chittem bark'. Bark must be aged at least 1 year to destroy harsh anthrone compounds.
Principal OTC laxative in North America for much of the 20th century; still used short-term for constipation.
Removed from FDA OTC monograph in 2002 due to lack of efficacy/safety data; still sold as dietary supplement.
spa Parts Used
bark
- short-term constipation
Only aged (>1 year) dried bark from trunk/branches is used - fresh bark contains free anthrones that cause violent vomiting and cramping.
shield Safety
Contraindications — Evidence Basis
Pregnancy
Anthraquinone laxatives may stimulate uterine activity; insufficient safety data.
Lactation
Anthranoids distribute into breast milk and may cause diarrhea in the nursing infant.
Children
Increased risk of dehydration, electrolyte disturbance, and hypokalemia.
Inflammatory bowel disease (Crohn's, ulcerative colitis)
Stimulant laxatives may aggravate mucosal inflammation and cause cramping.
Use >1 week / long-term use
Risk of dependence, electrolyte imbalance, hypokalemia, melanosis coli, and rare hepatotoxicity.
Concurrent use of cardiac glycosides (digoxin) or thiazide diuretics
Hypokalemia from chronic anthraquinone use potentiates cardiac glycoside toxicity.
Monitoring Parameters
Monitor during use, especially with prolonged or high-dose therapy.
Serum potassium
If used >1 week: weeklyRisk of hypokalemia from chronic anthraquinone use.
flagThreshold: K+ <3.5 mEq/L: discontinue and replete.
Liver enzymes (ALT, AST, ALP, bilirubin)
If used long-term: at baseline, 4 weeks, and as indicatedRare reports of cholestatic hepatitis, portal hypertension, and acute liver failure with chronic use.
flagThreshold: ALT >3x ULN or new jaundice: discontinue immediately and evaluate.
Toxicity
Use >1 week or doses above 20-30 mg hydroxyanthracene derivatives per day increase risk of toxicity. Fresh bark is toxic (emesis).
Severe abdominal cramping, watery diarrhea, hypokalemia, dehydration, electrolyte loss, cardiac arrhythmia, muscle weakness, melanosis coli, rare cholestatic hepatitis, acute liver failure.
Discontinue immediately; rehydration and electrolyte correction; monitor potassium and liver enzymes; supportive care.
Adverse Effects
CYP Metabolism
Emodin has been shown to modulate CYP3A4 in vitro; clinical relevance at therapeutic doses unclear.
swap_horiz Interactions
Digoxin
Class: Cardiac glycoside
Chronic cascara use causes hypokalemia through loss of potassium in stool. Hypokalemia markedly potentiates digoxin binding to the myocardial Na+/K+-ATPase, precipitating digoxin toxicity (ventricular arrhythmias, AV block) even at therapeutic serum digoxin levels.
Contraindicated with chronic cascara use. If short-term use unavoidable, monitor serum potassium and digoxin level; correct hypokalemia promptly.
Furosemide
Class: Loop diuretic
Additive potassium and magnesium losses via stool (cascara) and urine (loop diuretic) can precipitate clinically significant hypokalemia, hypomagnesemia and arrhythmia risk.
Avoid chronic combined use. If combined, check serum potassium and magnesium within 1-2 weeks and supplement as needed.
Hydrochlorothiazide
Class: Thiazide diuretic
Thiazides and stimulant anthraquinone laxatives both deplete potassium; combined use increases risk of hypokalemia, muscle weakness and arrhythmia.
Limit cascara to short courses (<1-2 weeks). Monitor electrolytes every 2-4 weeks if chronic laxative use continues.
Prednisone
Class: Corticosteroid
Corticosteroids promote renal potassium excretion; concurrent stimulant laxative use amplifies kaliuresis and risk of hypokalemic complications (weakness, ileus, arrhythmia).
Avoid chronic co-use. If both needed short-term, check potassium at 1 week.
Warfarin
Class: Anticoagulant
Reports of elevated INR with chronic anthraquinone laxative use, potentially from electrolyte-mediated vitamin K-epoxide cycle disturbance, reduced vitamin K absorption due to rapid GI transit, and possible direct displacement of warfarin from albumin.
Monitor INR closely if cascara is used >1 week alongside warfarin. Prefer bulk-forming laxatives (psyllium) in anticoagulated patients.
Oral contraceptives (combined)
Class: Hormonal contraceptive
Rapid intestinal transit induced by stimulant laxatives can reduce absorption of orally administered estrogens and progestogens, lowering contraceptive reliability.
Space cascara doses at least 2 hours apart from oral contraceptive dosing. Consider backup contraception with prolonged cascara use.
Licorice-containing medications (carbenoxolone)
Class: Mineralocorticoid / mucosal protectant
Both cascara (K loss via stool) and carbenoxolone/licorice (pseudohyperaldosteronism) reduce serum potassium; risk of severe hypokalemia and myopathy is additive.
Do not combine. If encountered, check serum potassium immediately and discontinue laxative.
hub Combinations
Synergistic pairings can enhance therapeutic outcomes, while knowing suitable substitutes helps when specific herbs are unavailable or contraindicated.
Possible Substitutes
2Aloe Vera
Moderate EvidenceBoth are anthraquinone-based stimulant laxatives; aloe latex is a stronger alternative.
Historical OTC formulations; both have similar FDA safety concerns.
Senna
Strong EvidenceSimilar anthraquinone mechanism; senna is the most commonly used clinically acceptable alternative.
Senna has FDA approval and stronger safety data.
Synergistic Combinations
2Fennel
Traditional UseFennel's carminative action reduces griping and abdominal cramping associated with stimulant laxatives.
Traditional Western formulation practice to temper anthraquinone cramping.
Psyllium
Moderate EvidenceBulking fiber combined with stimulant laxative improves stool formation and reduces dependence risk.
Standard combination in some OTC laxatives.
science Studies
Cytotoxicity of Structurally Diverse Anthranoids and Correlation with Mechanism of Action and Side Effects
In VitroThis in vitro study evaluated the cytotoxicity and apoptosis-inducing ability of structurally diverse anthraquinones including cascarosides A-F isolated from Rhamnus purshiana (cascara sagrada) bark. Cell viability was assessed in NOK-SI, HeLa, and T98G cell lines, and key apoptotic proteins were evaluated. The study found that glycosylated anthraquinones (cascarosides) showed notably reduced cytotoxicity compared to aglycone anthraquinones, providing mechanistic evidence that cascarosides-enriched cascara extract may have a safer laxative profile. The presence of glucose moieties in cascarosides appears to reduce cellular toxicity while retaining laxative activity through bacterial hydrolysis in the large intestine. These findings help explain the traditional use of cascara as a laxative at appropriate doses.
The metabolism of anthranoid laxatives
ObservationalThis foundational pharmacological review characterizes the metabolic fate of anthranoid laxatives including the cascarosides present in cascara sagrada. Anthranoid glycosides are demonstrated to pass through the small intestine unabsorbed, reaching the large intestine where colonic bacteria hydrolyze the sugar moiety to release active anthrone aglycones. The active metabolites then stimulate water and electrolyte secretion, promoting bowel movements. Radiochemical studies showed tissue-bound anthranoid activity clearance from most organs, with notable kidney retention. The review argues that anthrone C-glycosides (the primary active compounds in cascara) have a preferable safety profile compared to O-glycoside anthraquinones found in senna. These mechanistic insights remain the pharmacological basis for cascara's clinical use as a stimulant laxative.
medication Dosing
capsule
100-300 mg dried bark extract (standardized to 20-30 mg hydroxyanthracene derivatives)
Once at bedtime
Strictly short-term; do not exceed 7 days consecutive use. Takes effect in 8-12 hours.
tincture
2-6 mL fluid extract
Once at bedtime
Short-term use only. Mild bitter action.
decoction
1 g dried aged bark
Once at bedtime
Simmer 10 minutes; taken occasionally for constipation.
Disclaimer: This information is largely AI-generated and reviewed by human experts at Evara Health. It is intended for educational and clinical reference purposes only and should not replace professional medical advice.
© 2026 Evara Health. All rights reserved.