A woman with painful menstrual periods, or primary dysmenorrhea, has moderate to severe lower abdominal pain that occurs during the menstrual period. Primary dysmenorrhea is most common in women between the ages of 15 and 25.

The exact cause for painful menstrual periods is not clear. It may be due to an elevated production of prostaglandin hormones, which cause the uterus to contract. The contractions cause pelvic pain and cramps.