3 Herb Mamas

Wednesday’s Weeds: PENNYROYAL


American Pennyroyal (Hedeoma pulegioides) surrounded by Clovers, Wood Sorrel and Smartweed.

Both American (Hedeoma pulegioides) and European Pennyroyal (Mentha Pulegium) contain pulegone and have been used interchangeably. This fragrant terpenoid ketone is one that can provide potent benefits or fatal consequences depending upon how it is used. Finding a patch of this useful plant along a woodland edge delighted me and came at a perfect time when I was considering potency and responsible use of herbs and their essential oils. Pennyroyal is the perfect herbal poster child for this topic. 

Dried Pennyroyal can be used in pet bedding and rolled up in a bandanna tied around a pet’s neck to deter fleas. Some dogs will roll in a patch when they come across it, effectively self-treating themselves instinctively. Humans, too, can tuck a little of the crushed fresh stems and leaves into a hat band or bandanna to repel gnats. Although I have not tried it yet (but I will!), Pennyroyal is said to be a natural deterrent to flea beetles that love to devour eggplant. Companion planting and/or spraying a strong tea of Pennyroyal on leaves seems like a good approach. 

Sounds like a wonderful plant, doesn’t it? And it is. However, too much pulegone can result in miscarriage for pregnant humans and animals, liver toxicity, and even death. Many sources caution against internal use at all. The essential oil of Pennyroyal can definitely be dangerous to use. Remember, this is a very good plant used properly and responsibly. 

According to a Mother Earth New article (“What You Need to Know About Pennyroyal,” October 10, 2008), in a well-documented 1994 case a college student died after ingesting two teaspoons of Pennyroyal essential oil over a two day period. In another case, a healthy dog died after licking his fur after a similar amount had been applied. These cases highlight a very important issue that has the potential to do a lot of damage. It makes me think of the old adage that, A little bit of knowledge can be a dangerous thing. Knowing that Pennyroyal is an excellent insect repellent = good information. Access without education to those handy little bottles of essential oil that don’t require gathering, dehydrating, preparing, etc. CAN = a very bad thing. 

Something to consider with most essential oils is that a single drop of this very concentrated volatile oil, when ingested is the equivalent of drinking 28 cups of tea from the same plant! Two teaspoons of essential oil would be a massive dose. Is Pennyroyal (or other) essential oil bad? Of course not. But the misuse of it could prove tragic. 

The reason I said that stumbling across Pennyroyal in my forest garden was timely and perfect is because I am seeing a lot of mis-information being shared on the internet lately regarding both the internal and external use of essential oils. Their popularity is growing and the risks are significant. I’ve seen severe burns from externally applying the wrong essential oils “neat” (undiluted in a carrier oil) although the “aromatherapy consultant” had told the client it was perfectly safe. Whenever we apply externally or ingest internally any herb, food, or other healing agent or procedure we should ALWAYS do the research and inform ourselves of the potential risks and benefits. I am so thankful for my good teachers and mentors who insisted that I substantiate any and all health claims from at least three sources. That meant three different sources, not three books by the same author (or today that might mean three reference cites by one internet source or company, and I might be inclined to up the number to at least half a dozen given the plethora of copy and paste style references). That holds true today. No one else will know your precise sensitivities, allergies, or state of health so it is up to each of us to educate ourselves and make the best decisions we can based on the information and options available. 


Happy (and hopefully pest-free) Dog Days! ~Leenie



Leave a comment »