Pennyroyal consists of the dried leaves and flowering tops of Mentha Pulegium, Linn. (N.O. Labiatae), a plant which is indigenous to Britain and most parts of Europe. The stem is very much branched and prostrate or erect, the leaves are petiolate, ovate, and from 6 to 18 millimetres long, the whorls are all separate, and the calyx and pedicels pubescent or hispid. Odour, strong and characteristic; taste, pungent.
Constituents.—The chief constituent of pennyroyal is the volatile oil (see Oleum Pulegii).
Action and Uses.—Pennyroyal has similar properties to peppermint, and is used as an antispasmodic, but it is somewhat more irritant to the genito-urinary tract during excretion, and may thus reflexly augment uterine movements; it is, therefore, also used as an emmenagogue. The volatile oil is chiefly employed.
Dose.—2 to 4 grammes (30 to 60 grains).
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.