Pain relievers are useful in treating menstrual cramps because they are associated with increased prostaglandin levels during menstruation. During menstruation, the lysosomal enzymes dissolve the endometrial cells, so a large amount of prostaglandins are released causing excessive contraction of the smooth muscle of the uterus resulting in vasospasm, causing ischemia and hypoxia in the uterus, resulting in symptoms of dysmenorrhea. Most pain relieving drugs mainly refer to prostaglandin synthase inhibitors, which can inhibit the activity of prostaglandin synthase, reduce the production of prostaglandins, prevent uterine contraction and spasm and eliminate dysmenorrhea. They are usually started before the onset of menstruation and taken for 2-3 days. The main drugs are ibuprofen, ketoprofen, diclofenac potassium, etc.