This section is from the book "Materia Medica: Pharmacology: Therapeutics Prescription Writing For Students and Practitioners", by Walter A. Bastedo. Also available from Amazon: Materia Medica: Pharmacology: Therapeutics: Prescription Writing for Students and Practitioners.
These are remedies which tend to bring on the menstrual flow. They are:
2. Strong purgatives, as aloes, jalap, castor oil.
In early pregnancy any of these measures except those of the first and last groups may result in abortion, so an emmenagogue is also an abortifacient. Such substances as corn-smut, cotton-root bark, viburnum, valerian, and the strong volatile oils (rue, tansy, pennyroyal, etc.) have been shown to be without stimulating action. Lieb states that "the uterine colic which results from irritant cathartics or (so-called) emmenagogue oils is not due to direct stimulation of the uterus, but is purely reflex." Many volatile oils tend rather to overcome uterine colic.