It is not normal for a woman to have a blood clot during her menstrual period. Normal female menstrual blood is dark red in color and contains a large amount of fibrinolytic enzymes in the endometrium, so the menstrual blood is not clotted. However, when there is a large amount of bleeding in a short period of time, it can cause a relative shortage of fibrinolytic enzymes. Some menstrual blood appears to clot and clots appear, mostly on the second or third day of menstruation easily, and the clots no longer appear as the menstrual flow gradually decreases. However, if the clots are present throughout the menstrual period, it is easy to cause anemia symptoms. The use of blood-boosting drugs before menstruation, heavy alcohol consumption, strenuous physical activity during menstruation, and sexual intercourse during menstruation can easily cause excessive menstrual flow. In addition, disturbance of sex hormone level, high estrogen level or insufficient progesterone can also cause blood clots in menstruation. If the blood volume is high, the blood should be stopped before hormone treatment. If the blood volume is low most of them are exfoliated endometrium, if necessary, you can use herbs to activate blood circulation, remove blood stasis and warm yang to regulate.