Black Walnut

BotanicalBest with a meal

What is it

Black walnut (Juglans nigra) is a North American tree whose green hull is used in traditional herbalism for parasites and skin conditions; the nut itself is also edible.

Evidence for 1 use

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

Traditional antiparasitic use

Mixed Evidence

Lab activity is documented; human clinical trials for parasitic infection are absent.

How it works

Black walnut green hull contains juglone, a naphthoquinone with antibacterial, antifungal, and antiparasitic activity in lab studies. Tannins in the hull provide astringent activity used traditionally for diarrhea and skin conditions. Clinical evidence for antiparasitic use in humans is limited; lab activity does not necessarily translate to clinical efficacy.

Dosage

No RDA. Tincture dosing 15-30 drops three times daily; capsules 200-500 mg of hull powder.

When and how to take it

WHEN: With meals. HOW: Use short-term courses rather than continuous daily use.

2 commercial forms

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

Green hull tincture

Traditional liquid form.

Captures juglone and tannins.

Hull powder capsule

Common alternative form.

Tannin-rich.

Safety

Generally tolerated short-term. Juglone is potentially mutagenic in lab assays; long-term high-dose use is not recommended. The hull stains skin and clothing brown.

Who should be cautious

Avoid in pregnancy and tree nut allergy. Avoid long-term high-dose use due to juglone concerns.

Interactions

No significant interactions reported. Theoretical interactions with anticoagulants via tannins.

Food sources

Black walnut kernels (edible)

Amount
1 oz
%DV
—

Frequently asked questions

Does black walnut kill parasites?⌄

Lab studies show activity. Human clinical evidence for actual parasitic infections is lacking; clinician guidance is preferred.

References

Black Walnut on Wikidata — Wikidata link

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

Research on Black Walnut (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.