Bistort

Botanical

What is it

Bistort (Polygonum bistorta, now classified as Bistorta officinalis) is a perennial herb whose root is rich in tannins and has been used in European folk medicine as an astringent for diarrhea, mouth and throat inflammation, and minor bleeding.

Evidence for 2 uses

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

Diarrhea (astringent)

Mixed Evidence

Traditional astringent for acute diarrhea. Limited modern clinical evidence.

Sore throat and oral inflammation

Mixed Evidence

Traditional gargle use; limited modern evidence.

How it works

Bistort root contains 15 to 20 percent tannins (mostly hydrolyzable tannins), flavonoids, and gallic acid. The tannins bind to surface proteins of mucous membranes, producing the astringent effect that underlies its traditional uses for diarrhea and topical applications.

Dosage

Traditional: 1 to 3 grams of dried root powder as decoction, or 2 to 5 mL of tincture, several times daily.

When and how to take it

Traditional use spread across the day; separate from iron supplements.

1 commercial form

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Dried bistort root

Powdered root, capsules, or tinctures.

Tannins act locally.

Safety

Tannin-rich preparations can cause nausea and constipation. Long-term high-dose use may reduce mineral absorption.

Who should be cautious

Avoid in pregnancy and breastfeeding due to insufficient safety data. Use cautiously with chronic constipation.

Interactions

Tannins can reduce absorption of iron and certain medications. Avoid co-administration with iron supplements.

Frequently asked questions

Is bistort safe for daily use?⌄

Short-term use is generally well tolerated. Long-term high-dose tannin intake is not recommended.

References

Bistort on Wikidata — Wikidata link

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

Research on Bistort (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.