The main reason why dysmenorrhea occurs in Western medicine is related to the following factors: 1. primary dysmenorrhea, often without other underlying diseases, but manifested as stomach pain when menstruating, mainly during the menstrual period, the endometrial secretion of prostaglandins increases, so that the uterus will contract and strengthen, resulting in pain in the lower abdomen. 2. secondary dysmenorrhea It is often secondary to a disease, such as pelvic inflammatory disease, which causes pelvic congestion during menstruation and causes pain in the uterus or adnexa, which are originally inflamed. There is also dysmenorrhea caused by endometriosis. This condition can cause pain in the lower abdomen because the ectopic lesion also bleeds during menstruation. In other cases, the uterus is deformed, so that when menstruation occurs, the uterus has to contract to remove menstrual blood, and the contraction of the uterus is deformed and uncoordinated, causing menstrual pain.