Women may use emmenagogues to stimulate menstrual flow when menstruation is absent for reasons other than pregnancy, such as hormonal disorders or conditions like oligomenorrhea (infrequent menses).
According to Riddle,[1][page needed] these herbs were also used to assist women whose menstruation was "delayed", for the reason that they had conceived.
There are a large number of substances which can act as emmenagogues.
Many, such as Mentha pulegium, European pennyroyal, or tansy, may bring on menses when administered as a tea.
However, if a concentrated dose is taken, such as by consuming an oil, they can pose serious medical risks including organ damage and incomplete abortions.