Quick Summary

Pennyroyal (Mentha pulegium) is a medicinal herb from the Mentha genus that has traditional uses and is the subject of ongoing research. Current clinical evidence is limited and sometimes conflicting. Some observational data indicate potential associations with anthropometric changes, including skeletal muscle percentage. Related Mentha species have demonstrated antimicrobial properties in preclinical studies; however, specific clinical benefits of Pennyroyal remain under-investigated.

What is it?

Pennyroyal is a perennial herb belonging to the mint family (Lamiaceae). It is native to Europe, North Africa, and parts of Asia and has been historically used in herbal medicine. The plant is known for its aromatic leaves and has been traditionally utilized for various purposes within folk medicine.

Traditional Uses

Traditionally, Pennyroyal has been used as a digestive aid and for its aromatic and insect-repellent properties. It has also been employed in folk remedies for gastrointestinal discomfort and as a stimulant, although contemporary scientific support for these uses is limited.

Active Compounds

Pennyroyal contains essential oils rich in compounds such as pulegone, which is known for its biological activity. These constituents have been studied in related Mentha species for antimicrobial and other effects, but precise active mechanisms in Pennyroyal require further research.

Potential Benefits with Evidence Levels

  • Association with anthropometric indices and skeletal muscle percentage: Low to moderate clinical evidence from a cross-sectional observational study with 662 participants suggested that weekly or daily intake of Pennyroyal was associated with a higher skeletal muscle percentage (P < 0.05). This evidence is observational and hypothesis-generating, not confirming causality.
  • Potential antimicrobial and wound healing properties (from related Mentha species): Preclinical in vitro and animal studies indicate that essential oils from Mentha species may have antimicrobial activity and promote wound healing. However, no direct clinical trials have specifically evaluated Pennyroyal for these effects.
  • Effect on functional dyspepsia symptoms: Moderate clinical evidence from a systematic review of randomized controlled trials found little to no significant improvement in functional dyspepsia symptoms with Pennyroyal compared to placebo (standardized mean difference -0.38; moderate certainty).

Side Effects

  • Potential convulsant effects attributed to compounds such as pulegone
  • Possible hepatotoxicity suggested by data on some Mentha-derived products
  • Photosensitisation and toxicity have been reported with related Mentha species
  • Cases of contact dermatitis have been documented

Drug Interactions

There are no high-quality clinical data on Pennyroyal-specific drug interactions. However, herb-drug interactions are a recognized concern with herbal products, particularly those affecting cytochrome P450 enzymes. Caution is advised when taking Pennyroyal alongside other medications.

Who Should Avoid It

  • Pregnant and breastfeeding women, due to insufficient safety data and potential risks from constituent compounds
  • Individuals with known or suspected liver disease, given potential hepatotoxicity concerns
  • People with epilepsy or seizure disorders, because of the potential for convulsant effects

Evidence Limitations

  • Lack of randomized controlled trials specifically evaluating Pennyroyal in humans
  • Most evidence derives from preclinical studies or observational reports
  • Conflicting and insufficient clinical data regarding efficacy for gastrointestinal or other indications
  • Safety data primarily extrapolated from related Mentha species and essential oil toxicity studies rather than Pennyroyal alone

References

Last Reviewed

June 2024

Informational Disclaimer

This information is provided for educational purposes only and is not intended as medical advice. Pennyroyal may have risks and potential side effects. Consult a healthcare professional before using Pennyroyal or any herbal supplement, especially if you are pregnant, nursing, have underlying health conditions, or are taking medications. Research on Pennyroyal is ongoing, and current evidence is limited and inconclusive.