Cascara
Frangula purshiana (syn. Rhamnus purshiana)
Cascara sagrada is a stimulant laxative bark from the Pacific Northwest, effective for short-term constipation relief but unsuitable for regular use because of dependence, electrolyte loss and liver concerns.
At a Glance
- Best known for
- Reliable short-term relief of occasional constipation, Stimulates colonic motility within 6–12 hours, Traditional bowel-preparation and 'cleansing' use
- Evidence
- Moderate
- Typical dose
- 300–1000 mg aged bark extract at bedtime
- Type
- Herb
What is Cascara?
Cascara sagrada ('sacred bark' in Spanish) is the dried, aged bark of Frangula purshiana, a buckthorn tree native to the Pacific coast of North America. Indigenous peoples used it as a purgative, and from the late 1800s it became one of the most widely used laxative ingredients in North America and Europe. The bark must be aged for at least a year (or heat-treated) before use, because fresh bark contains free anthrones that cause severe vomiting and griping. In 2002 the US FDA removed cascara from over-the-counter laxative products because manufacturers did not submit the safety data the agency requested; it remains available as a dietary supplement and herbal tea.
Known Health Benefits
How It Works
Cascara's anthraquinone glycosides pass through the small intestine unabsorbed. In the colon, gut bacteria cleave off the sugar groups to release active anthrones, which irritate the colonic lining, stimulate peristalsis via the myenteric plexus, and shift water and electrolyte transport so that less fluid is absorbed and more is secreted into the bowel. The combined effect is a softer stool and a bowel movement typically 6–12 hours after a dose. Because the action depends on bacterial activation, the effect is delayed and dose-dependent, and it does not occur in the small intestine.
What Research Says
Stimulant anthraquinone laxatives as a class have decades of clinical use and controlled trials confirming they produce bowel movements more reliably than placebo in short-term constipation, but cascara specifically has far fewer modern randomized trials than senna or bisacodyl. Most cascara data come from older comparative trials, bowel-preparation studies and pharmacology work. Case reports describe cholestatic hepatitis and portal hypertension with heavy use, and observational studies link long-term stimulant laxative use to melanosis coli (a benign pigmentation) and hypokalemia. Earlier concerns about anthraquinones and colorectal cancer have not been confirmed in human cohorts. The honest summary: cascara works for short-term constipation, but its evidence base is thin, its regulatory status is unfavorable, and better-studied alternatives such as psyllium, polyethylene glycol and senna exist.
Active Compounds
Hydroxyanthracene glycosides (cascarosides A–D, aloins, chrysaloins), emodin, aloe-emodin
Forms & Bioavailability
The glycosides are poorly absorbed intact, which is intentional: they need to reach the colon for bacterial activation. Small amounts of the aglycones (emodin, aloe-emodin) are absorbed, metabolized in the liver and excreted in urine and breast milk, where they can discolor urine reddish-brown. Products should state the cascaroside content; raw bark that has not been aged is unsafe and unpredictable in potency.
Dosage Guidance
| Use Case | Dosage |
|---|---|
| Occasional constipation (adults) | 300–1000 mg aged bark extract at bedtime |
| Liquid extract | 2–5 mL (1:1) at bedtime |
| Bark decoction | 1–2 g in 150 mL water, once daily |
| Maximum duration | No more than 7–10 consecutive days |
Always consult a healthcare provider for personalized dosing.
Natural Food Sources
- None — cascara is not a food plant
- Sometimes added to herbal 'detox' or 'cleanse' teas (check labels)
Potential Side Effects
Abdominal cramping, diarrhea, electrolyte (potassium) loss, laxative dependence with regular use, melanosis coli, rare liver injury; fresh (uncured) bark causes vomiting
Who Should Avoid It
- Intestinal obstruction, ileus, appendicitis or undiagnosed abdominal pain
- Inflammatory bowel disease (Crohn's disease, ulcerative colitis) during flares
- Children under 12 (and under 18 for regular use)
- Pregnancy and breastfeeding
- Known liver disease or concurrent hepatotoxic drugs
Pregnancy & Lactation
Cascara is not recommended in pregnancy: anthraquinone laxatives can stimulate uterine contractions in theory and cause maternal electrolyte loss, and safer options (fiber, fluids, polyethylene glycol) exist. Anthraquinone metabolites pass into breast milk and may cause loose stools in a nursing infant; most references advise avoiding it while breastfeeding.
Known Drug Interactions
Potassium loss increases toxicity of digoxin and additive effects with diuretics, corticosteroids and licorice; may reduce absorption of oral drugs by speeding transit; avoid with other stimulant laxatives
Evidence Classification
Supported by cohort studies, case-control studies, or multiple observational studies with consistent findings.
Frequently Asked Questions
Why was cascara removed from over-the-counter laxatives?
In 2002 the FDA reclassified aloe and cascara sagrada as 'not generally recognized as safe and effective' for OTC laxative use. This was not because new harms were proven, but because the manufacturers did not submit the carcinogenicity and safety data the agency asked for. Cascara can still be sold as a dietary supplement, which is a lower evidence bar. Treat this as a reason for caution and short-term use rather than proof of danger.
How is cascara different from senna?
Both are anthraquinone stimulant laxatives with similar mechanisms, timing and side effects. Senna has more modern clinical trials, standardized sennoside dosing and retains OTC approval, which is why most clinicians recommend it instead. Some people report cascara causes less cramping, but this has not been shown in controlled comparisons.
Can I take cascara every day for chronic constipation?
No. Daily stimulant laxative use can lead to reduced bowel responsiveness, dependence, low potassium and melanosis coli. Chronic constipation should be addressed with fiber (psyllium), fluids, magnesium, osmotic laxatives like polyethylene glycol, and medical evaluation if it persists more than a few weeks.
Is cascara coffee or cascara tea the same thing?
No. 'Cascara' in coffee shops refers to the dried husk of the coffee cherry (Coffea arabica), which is brewed as a mildly caffeinated tea. It has nothing to do with cascara sagrada bark and has no laxative effect.
References
- Status of certain additional over-the-counter drug category II and III active ingredients (aloe, cascara sagrada) — final rule. US Food and Drug Administration. Federal Register (2002)
- Cascara. In: LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. National Institute of Diabetes and Digestive and Kidney Diseases. NCBI Bookshelf (2020)
- Cholestatic hepatitis associated with cascara sagrada. Nadir A, Reddy D, Van Thiel DH. Am J Gastroenterol (2000)
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This entry is for educational purposes only. It is not medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement regimen, especially if you take medications or have health conditions.