Dysmenorrhea is defined clinically as pain in the lower abdomen before, during, or after menstruation. Pain in the stomach on the third day of menstruation is also clinically considered to be a type of dysmenorrhea. This condition is often caused by the following reasons: first, chronic inflammation of the pelvis. The second one is endometriosis. Due to the foci of endometriosis, bleeding can also occur during menstruation, so it can lead to lower abdominal pain. The third one, pain caused by malformation of uterine development. It is recommended to do a detailed gynecological examination after menstruation is clean, and ultrasound if necessary, mainly to understand the cause of dysmenorrhea, and then give the corresponding treatment according to the cause, so that the possibility of dysmenorrhea can be completely relieved. It is also possible that the pain in the stomach is caused by drinking a lot of frozen drinks during menstruation, so it is recommended to keep warm during menstruation.