1. Dysmenorrhea is severe cramping pain in the lower abdomen that occurs before or during menstruation. 2. There are two main types - primary, caused by prostaglandins, and secondary, caused by an underlying reproductive disorder like endometriosis. 3. Primary dysmenorrhea usually begins 6-12 months after menarche and involves lower abdominal pain radiating to the back or thighs lasting 48-72 hours.