Buckthorn

BotanicalBest before bed

What is it

Buckthorn (Frangula alnus, formerly Rhamnus frangula; also Rhamnus purshiana, cascara) is a deciduous shrub whose dried bark is used as a stimulant laxative.

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Short-term constipation

Good Evidence

Effective as a short-term stimulant laxative; long-term use is contraindicated.

How it works

Buckthorn bark contains anthraquinone glycosides (frangulins, glucofrangulins) that are converted by colonic bacteria to active anthrones. These stimulate colonic motility and inhibit water absorption, producing a laxative effect within 6-12 hours. Fresh bark contains higher levels of irritant compounds that cause vomiting; only properly aged (at least one year) bark is used medicinally.

Dosage

No RDA. Standardized preparations supply 20-30 mg of hydroxyanthracene derivatives per day, used short-term only.

When and how to take it

WHEN: At bedtime, expecting effect by morning. HOW: Short-term use only.

1 commercial form

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Aged dried bark or extract

Aging reduces gastric irritation.

Activated by colonic bacteria.

Safety

Stimulant laxatives are not for chronic use. Long-term use can cause electrolyte imbalance (especially potassium loss), dependence, and pseudomelanosis coli. EFSA has restricted hydroxyanthracene laxatives. Cramping is common.

Who should be cautious

Avoid in pregnancy, breastfeeding, intestinal obstruction, inflammatory bowel disease, children under 12, and chronic use beyond 1-2 weeks.

Interactions

Potassium loss can potentiate digoxin toxicity. May reduce absorption of co-ingested drugs due to faster transit.

Frequently asked questions

Can I use buckthorn daily?⌄

No. Limit to 1-2 weeks. Long-term use causes dependence and electrolyte issues.

References

Buckthorn on Wikidata — Wikidata link

Buckthorn on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Buckthorn (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.