Skip navigation

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

URL of this page: https://medlineplus.gov/druginfo/natural/480.html

Pennyroyal

What is it?

Pennyroyal (Mentha pulegium) is a plant that grows throughout the world. The leaves, and the oil they contain, are used to make medicine.

Pennyroyal essential oil contains chemicals that have various toxic effects in the body.

People use pennyroyal for the common cold, pneumonia, fatigue, ending a pregnancy (abortion), and as an insect repellant, but there is no good scientific evidence to support these uses. It is also unsafe.

How effective is it?

There is interest in using pennyroyal for a number of purposes, but there isn't enough reliable information to say whether it might be helpful.

Is it safe?

When taken by mouth: Pennyroyal essential oil is likely unsafe. It can cause serious liver and kidney damage, as well as nervous system damage. Repeated use may lead to death. There isn't enough reliable information to know if pennyroyal leaf is safe to use as a tea.

When applied to the skin: Pennyroyal essential oil is likely unsafe.

Special precautions & warnings:

Pregnancy: It is likely unsafe to take pennyroyal by mouth or apply it to your skin when pregnant. There is some evidence that pennyroyal oil can cause abortions by causing the uterus to contract. But the dose needed in order to cause an abortion could kill the parent or cause life-long kidney and liver damage. Avoid use.

Breast-feeding: It is likely unsafe to take pennyroyal by mouth or apply it to your skin while breast-feeding. Avoid use.

Children: Pennyroyal is likely unsafe when taken by mouth in children. Infants have developed serious liver and nervous system damage, and even death, after taking pennyroyal.

Kidney disease: Pennyroyal essential oil can damage the kidney and make existing kidney disease worse.

Liver disease: Pennyroyal essential oil can cause liver damage and might make existing liver disease worse.

Are there interactions with medications?

Moderate
Be cautious with this combination.
Acetaminophen (Tylenol, others)
Pennyroyal can cause liver damage. Taking pennyroyal with acetaminophen, which causes a similar type of liver damage, might increase the risk for liver damage.

Are there interactions with herbs and supplements?

Iron
Pennyroyal might reduce how much iron the body absorbs from supplements.

Are there interactions with foods?

Pennyroyal might reduce how much iron the body absorbs from food.

How is it typically used?

There isn't enough reliable information to know what an appropriate dose of pennyroyal might be. Pennyroyal is also unsafe. Speak with your healthcare provider before using.

Other names

American Pennyroyal, Dictame de Virginie, European Pennyroyal, Feuille de Menthe Pouliot, Frétillet, Hedeoma pulegioides, Herbe aux Puces, Herbe de Saint-Laurent, Huile de Menthe Pouliot, Lurk-In-The-Ditch, Melissa pulegioides, Mentha pulegium, Menthe Pouliot, Menthe Pouliote, Mosquito Plant, Penny Royal, Pennyroyal Leaf, Pennyroyal Oil, Piliolerial, Poleo, Pouliot, Pouliot Royal, Pudding Grass, Pulegium, Pulegium vulgare, Run-By-The-Ground, Squaw Balm, Squawmint, Stinking Balm, Tickweed.

Methodology

To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.

References

  1. Sebai E, Abidi A, Serairi R, et al. Essential oil of Mentha pulegium induces anthelmintic effects and reduces parasite-associated oxidative stress in rodent model. Exp Parasitol 2021;225:108105. View abstract.
  2. Ajebli M, Eddouks M. Vasorelaxant and Antihypertensive Effects of Mentha pulegium L. in Rats: An In vitro and In vivo Approach. Endocr Metab Immune Disord Drug Targets 2021;21:1289-1299. View abstract.
  3. Farid O, Zeggwagh NA, Ouadi FE, Eddouks M. Mentha pulegium aqueous extract exhibits antidiabetic and hepatoprotective effects in streptozotocin-induced diabetic rats. Endocr Metab Immune Disord Drug Targets 2019;19:292-301. doi: 10.2174/1871530318666181005102247. View abstract.
  4. Fozard J, Hieger M. Hepatic failure from pennyroyal tea interaction with medications metabolized by the cytochrome P450 enzymes. Am J Ther 2019 Aug 13. doi: 10.1097/MJT.0000000000001052. [Epub ahead of print]. View abstract.
  5. Vaghardoost R, Ghavami Y, Sobouti B. The effect of Mentha pulegium on healing of burn wound injuries in rat. World J Plast Surg 2019;8:43-50. doi: 10.29252/wjps.8.1.43. View abstract.
  6. Hurrell RF, Reddy M, Cook JD. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. Br.J Nutr 1999;81:289-295. View abstract.
  7. Sullivan JB Jr, Rumack BH, Thomas H Jr, et al. Pennyroyal oil poisoning and hepatotoxicity. JAMA 1979;242:2873-4. View abstract.
  8. Anderson IB, Mullen WH, Meeker JE, et al. Pennyroyal toxicity: measurement of toxic metabolite levels in two cases and review of the literature. Ann Intern Med 1996;124:726-34. View abstract.
  9. Sudekum M, Poppenga RH, Raju N, Braselton WE Jr. Pennyroyal oil toxicosis in a dog. J Am Vet Med Assoc 1992;200:817-8.. View abstract.
  10. Bakerink JA, Gospe SM Jr, Dimand RJ, Eldridge MW. Multiple organ failure after ingestion of pennyroyal oil from herbal tea in two infants. Pediatrics 1996;98:944-7. View abstract.
  11. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  12. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  13. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  14. Martindale W. Martindale the Extra Pharmacopoeia. Pharmaceutical Press, 1999.
  15. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  16. Foster S, Tyler VE. Tyler's Honest Herbal: A Sensible Guide to the Use of Herbs and Related Remedies. 3rd ed., Binghamton, NY: Haworth Herbal Press, 1993.
  17. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
Last reviewed - 09/28/2022