These are remedies which tend to bring on the menstrual flow. They are:

1. Local measures, as hot or mustard foot- or sitz-baths, hot-water bottle or counterirritant drugs (turpentine, mustard) to lower abdomen, hot vaginal douches.

2. Strong purgatives, as aloes, jalap, castor oil.

3. Genito-urinary irritants, as cantharis.

4. Drugs which stimulate the uterine muscle, as ergot, hydrastis, quinine, and caulophyllum (blue cohosh). Pilcher found prompt contraction of uterine strips from caulophyllum.

5. Measures to improve the general health, as iron, cod-liver oil, strychnine; in heart disease, digitalis; in tuberculosis, dry cool air.

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.