In TCM, Irregular menstruation is usually due to emotional factors, or attack by exogenous cold, heat and dampness that impair the thoroughfare and conception vessels and affect the functions of the viscera and the balance between qi and blood as well as that between yin and yang. Clinically changes of cycle and quantity usually appear simultaneous in irregular menstruation, though there is difference between the change of cycle and the change of quantity.

For example, early menstruation is usually profuse and delayed menstruation is often scanty. Scanty early menstruation and profuse delayed menstruation are either of asthenia or of sthenia, and due to either cold or heat. Syndrome differentiation of irregular menstruation for deciding treatment should be done according to the period,quantity, color and nature of menses as well as the conditions of the tongue and pulse.