It increased nutrient absorption in the intestines. Pennyroyal is used in folk medicine to facilitate digestion. This property is also reportedly present in its essential oil and it promotes digestion by stimulating the secretion of digestive juices. Pennyroyal essential oil is sometimes used in herbal medicine as an emmenagogue.
English herbalist Nicholas Culpeper wrote about some uses for the plant including its role in women's ailments, venomous bites, and digestion. European settlers used the plant for respiratory ailments, mouth sores, and female disorders. The plant's oil has been used as a flea-killing bath, and has been used externally as a rubefacient (counter-irritant).