Primary menstrual cramps is pelvic pain that occurs when the uterus contracts to remove the blood and endometrial lining that accumulates monthly when an embryo is not implanted in the uterus. The pains may last about 1 to 7 days during a female's menstrual cycle. Medication, home remedies (OTC medication, heating pads, etc.), lifestyle changes (for example, regular exercise, sufficient sleep), may reduce these symptoms. Secondary menstrual cramps (secondary dysmenorrhea) are caused by other conditions or diseases, not regular menstruation (for example, endometriosis, fibroids, ovarian cysts, pelvic inflammatory disease).