Frangula

BotanicalBest before bed

What is it

Frangula (Frangula alnus or Rhamnus frangula), commonly called alder buckthorn, is a shrub whose dried, aged bark is used as a stimulant laxative similar to senna.

Evidence for 1 use

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

Short-term constipation relief

Good Evidence

Recognized laxative herb with mechanism similar to senna; clinical evidence is largely from older studies and herbal monographs.

How it works

The bark contains anthraquinone glycosides (frangulins) that are converted by colon bacteria to active forms that stimulate intestinal motility and water secretion. Fresh bark is not used because it causes severe vomiting; aging or heat-treatment of the bark for at least a year is required.

Dosage

Standardized to deliver about 10-30 mg of hydroxyanthracene derivatives (as frangulin) per day, taken at bedtime.

When and how to take it

Taken at bedtime for next-morning effect. Not for daily long-term use.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

Aged frangula bark

Traditional preparation.

Anthraquinones activated by colon bacteria; effect develops over hours.

Standardized fluid or solid extract

Modern herbal product.

Consistent anthraquinone dosing.

Safety

Effective short-term laxative. Chronic use can cause electrolyte abnormalities (potassium loss), dependence, and melanosis coli. Should not be used long-term without medical supervision.

Who should be cautious

Avoid in suspected bowel obstruction, IBD flares, severe dehydration, and pregnancy/breastfeeding. Not for children under 12 without medical advice. Never use fresh bark.

Interactions

Potassium loss can affect cardiac glycosides (digoxin), diuretics, and corticosteroids. May reduce absorption of other oral medications.

Food sources

Not a food

Amount
n/a
%DV
—

Frequently asked questions

Is frangula the same as cascara?⌄

Both are anthraquinone-containing Rhamnaceae plants with similar laxative action. Cascara sagrada (Rhamnus purshiana) is a different species but pharmacologically similar.

Can I use frangula daily?⌄

Not for prolonged periods. Chronic stimulant laxative use can cause dependency and electrolyte problems. Address underlying constipation causes first.

References

Frangula on Wikidata — Wikidata link

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

Research on Frangula (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.