Pennyroyal in therapeutics
Pennyroyal refers to two plants, Mentha pulegium (European pennyroyal) and Hedeoma pulegioides (American pennyroyal), both part of the mint family. Historically, it has been used in traditional medicine in Europe and North America for various ailments, including colds, coughs, kidney issues, and even to induce abortions. However, it is crucial to note that pennyroyal is toxic, particularly to the liver, and has caused serious health issues, including fatalities, when used improperly. The essential oil of pennyroyal contains pulegone, which can convert to a harmful substance called menthofuran, leading to severe neurological symptoms and potential liver failure. Due to its associated health risks and lack of proven efficacy in medical applications, the use of pennyroyal is not recommended, even for topical applications as an insect repellent. Allergic reactions and skin irritation can also occur with topical use. Thus, caution and awareness of its dangers are essential for anyone considering the use of pennyroyal in any form.
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Subject Terms
Pennyroyal in therapeutics
- DEFINITION: Natural plant product used to treat specific health conditions.
- PRINCIPAL PROPOSED USES: None recommended
Overview
The name pennyroyal refers to two related plants: Mentha pulegium (European pennyroyal) and Hedeoma pulegioides (American pennyroyal). Pennyroyal is a member of the mint family. Applied topically, pennyroyal has been used since Ancient Greece to repel fleas and other insects. Pennyroyal has been taken internally in Europe and North America for a variety of conditions, including colds and influenza, coughs, kidney problems, headache, and upset stomach, as well as to induce abortion. Traditional herbalists do not appear to have noticed an essential fact about pennyroyal—it is toxic to the liver. In modern times, people have died as a consequence of using this herb for traditional indications.
The essential oil of pennyroyal contains a substance called pulegone. In the body, pulegone is converted to the toxic chemical menthofuran. Low levels of menthofuran may not produce any untoward effects. At a certain point, however, depending on the individual, menthofuran poisons the nervous system, causing symptoms such as dizziness, vertigo, hallucinations, and possibly unconsciousness. Liver damage, possibly leading to liver failure, occurs subsequently. Further, pennyroyal could also cause kidney damage and severe neurological effects, such as seizures and paralysis. In severe cases, pennyroyal can lead to death.
Because of these safety risks and the fact that pennyroyal has not been proven effective for any medical use, this herb should be avoided entirely. It is not even recommended for use topically as an insect repellant because it is possible that enough pulegone could be absorbed to cause harm. Additionally, topical application of pennyroyal can lead to allergic reactions and skin irritation.
Bibliography
Anderson, I. B., et al. "Pennyroyal Toxicity: Measurement of Toxic Metabolite Levels in Two Cases and Review of the Literature." Annals of Internal Medicine, vol. 124, 1996, pp. 726-734.
Luís, Ângelo, and Fernanda Domingues. "Screening of the Potential Bioactivities of Pennyroyal (Mentha pulegium L.) Essential Oil." Antibiotics (Basel), vol. 10, no. 10, 2021, p. 1266, doi:10.3390/antibiotics10101266.
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