The herb Pennyroyal (Mentha pulegium), is a member of the mint family; an essential oil extracted from it is used in aromatherapy - note that as pennyroyal has a traditional folk medicine use in inducing abortions, pregnant women should avoid the use of the oil.

The oil is also used as a flea repellant for pets. This latter usage is the origin of the plant's Latin species name, the flea being Pulex irritans.