Menstrual pain, also called dysmenorrhea, refers to a period of time before and after menstruation, as well as pain in the lower abdomen, cramping, lumbago, and pain in the inner thighs during menstruation, which is more painful for patients and can affect normal life and work. Menstrual pain occurs for the following reasons: 1. Primary dysmenorrhea, without secondary factors, may be related to substances produced in the body when menstruation occurs, such as prostaglandins, vasopressin, uterine constrictors epinephrine, etc. These substances can cause excessive contraction of the uterus, and uterine ischemia and hypoxia occur, so dysmenorrhea can occur. If the uterus is severely posterior and the discharge of menstrual blood is poor, dysmenorrhea is also likely to occur. 2. Secondary dysmenorrhea is caused by other gynecological diseases, such as endometriosis, adenomyosis, pelvic inflammatory disease, uterine fibroids, endometrial polyps, etc., which can easily lead to dysmenorrhea, and requires treatment of the primary disease before the dysmenorrhea can improve.