European Pennyroyal

Botanical

What is it

European pennyroyal (Mentha pulegium) is a mint family herb. Historically used as a flavoring, insect repellent, and abortifacient. It contains pulegone, a hepatotoxic essential oil compound, and is widely considered unsafe for internal use.

Evidence for 2 uses

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

Insect repellent (topical/external)

Limited Evidence

Pulegone repels insects; pennyroyal has historic use as a flea repellent in animal bedding (with caution regarding animal toxicity).

Abortifacient (historical, dangerous)

Mixed Evidence

Historical use as an abortifacient resulted in numerous maternal deaths. No legitimate medical use.

How it works

Pennyroyal essential oil is rich in pulegone (often greater than 80 percent), which is metabolized in the liver to menthofuran. Menthofuran depletes glutathione and produces a reactive metabolite that causes hepatocellular necrosis. Pennyroyal has historically been used as an abortifacient, but at doses that often cause severe maternal toxicity, including liver failure and death.

Dosage

There is no safe internal dose of pennyroyal essential oil. Traditional infusions of the dried herb in very small amounts have been used as flavorings, but use is strongly discouraged.

When and how to take it

Internal use is not recommended.

2 commercial forms

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

Pennyroyal essential oil

Should not be used internally.

Highly toxic when ingested.

Dried pennyroyal herb

Internal use discouraged.

Lower pulegone content than oil but still risky.

Safety

Serious hepatotoxicity and acute liver failure have been reported, including fatal cases. Pulegone is genotoxic in animal studies. The U.S. FDA does not approve pennyroyal essential oil for internal use.

Who should be cautious

Absolutely contraindicated in pregnancy (causes both abortion and severe maternal toxicity). Avoid in breastfeeding, children, and people with any liver disease. The essential oil should not be ingested under any circumstances.

Interactions

Avoid combining with any hepatotoxic drug or alcohol. Glutathione-depleting agents (acetaminophen at high doses) would amplify toxicity.

Frequently asked questions

Is pennyroyal safe to drink as tea?⌄

No. Even pennyroyal tea has caused serious liver toxicity. Avoid all internal use.

Can it cause death?⌄

Yes. Fatal cases of pennyroyal poisoning, particularly from essential oil and from use as an abortifacient, are documented.

Why is it in some products?⌄

Historical use persists in some traditional and herbal sources. Modern guidance is to avoid internal use entirely.

References

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

Research on European Pennyroyal (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.