Pennyroyal is the smallest of the mint family, and has some very distinctive properties. The taste and odor of pennyroyal is stronger and far more pungent than other mints, which makes it disagreeable to many people. It's also disagreeable to insects, and pennyroyal has been used as a natural insect repellant for centuries.
The use of pennyroyal oil in products has become controversial when products using the oil were implicated in the deaths of two women. The herb is known to be toxic when taken in large doses, and skin contact with the pure oil can cause dermatitis.
Volatile oil (0.5-1%) of which approx. 85% is a ketone, pulegone; also isopulegone, menthol, isomethone, limone, piperitone, neomenthol. There are also miscellaneous bitters, tannins, & flavone glycosides.
The entire aerial portion, preferably in the flowering stage.
Usually as a tea but sometimes in extract and seldom in capsules. Topically the oil or fresh herb can be used as an insect repellent, but in some cases may induce a rash or similar reaction.
The pure oil of pennyroyal can be highly toxic if ingested. Utilizing pennyroyal as an abortifacient is also considered quite dangerous as many serious complications and hemorrhaging may occur, therefore the herb should never be used in this manner. Pennyroyal is a good herb to plant in gardens to keep bugs away.