Description

Powerfully aromatic perennial growing to 16 in (40 cm). Has oval, toothed leaves and whorls of lilac flowers.

Habitat & Cultivation

Pennyroyal is native to Europe and western Asia, and has become naturalized in the Americas. It thrives in damp areas and is gathered when in flower in summer.

Parts Used

Aerial parts.

Constituents

Pennyroyal’s volatile oil contains pulegone (27–92%), isopulegone, menthol, and other terpenoids. Pennyroyal also contains bitters and tannins.

History & Folklore

The Roman natural historian Pliny (23–79 CE) wrote that pennyroyal was considered a better medicinal herb than roses, and that it purified bad water. His contemporary, Dioscorides, stated that pennyroyal “provokes menstruation and labour.” In 1597, John Gerard wrote that “a garland of pennie royal made and worne about the head is of great force against the swimming of the head, and the pains and giddiness thereof.” The name pulegium derives from the Latin word for flea, referring to pennyroyal’s traditional use as a flea-repellent.

Medicinal Actions & Uses

Similar in many respects to peppermint (M. x piperita), pennyroyal is a good digestive tonic. It increases the secretion of digestive juices, relieves flatulence and colic, and occasionally is used as a treatment for intestinal worms. It makes a good remedy for headaches and for minor respiratory infections, helping to check fever and reduce mucus.

Pennyroyal powerfully stimulates the uterine muscles and encourages menstruation. An infusion of pennyroyal can be used externally to treat itchiness and formication (a sensation of ants crawling over the body) and rheumatic conditions including gout.

Related Species

See peppermint (M. x piperita) and bo he (M. haplocalyx). American pennyroyal (Hedeoma pulegoides), while only distantly related, has constituents similar to those of pennyroyal. American pennyroyal is traditionally used as a remedy for colds, headaches, and delayed menstrual periods.

Cautions

Do not use the essential oil, which is highly toxic. Do not take pennyroyal during pregnancy, or if menstrual periods are heavy.