Painful menstrual cramps (dysmenorrhea) can occur during or just before your period. The cramping can involve your lower belly, back, or thighs. And the pain from these cramps can range from mild to severe.

Primary dysmenorrhea is a term used to describe painful menstrual cramping that isn't caused by a medical problem. It often starts during the teen years, when periods first start. But the pain often improves as you get older. Secondary dysmenorrhea is a term used to describe painful menstrual cramping caused by a medical problem, such as endometriosis, uterine polyps or fibroids, or pelvic infection. Menstrual-type cramps also may occur after a medical procedure, such as cautery, cryotherapy, or IUD insertion.