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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?

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?

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.


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


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Last reviewed - 01/04/2024