Menstrual cramps (dysmenorrhea) are throbbing or cramping pains in the lower abdomen. Many women experience menstrual cramps just before and during their menstrual periods. For some women, the discomfort is merely annoying. For others, menstrual cramps can be severe enough to interfere with everyday activities for a few days every month. During your menstrual period, your uterus contracts to help expel its lining. Hormone-like substances (prostaglandins) involved in pain and inflammation trigger the uterine muscle contractions. Higher levels of prostaglandins are associated with more-severe menstrual cramps.