pain or painful cramps felt before or during menstruation. Dysmenorrhea may be primary or secondary. Primary dysmenorrhea is caused by specific imbalances in the woman's endocrine system (endocrine system, human) during the menstrual cycle. Secondary dysmenorrhea denotes menstrual cramps caused by some other distinct organic disorder. In most cases dysmenorrhea is primary.

Primary dysmenorrhea may occur a few days before the period, at the onset of bleeding, or during the total episode. The pain varies from a severe incapacitating distress to relatively minor and brief intense cramps. Other symptoms may include irritability, fatigue, backache, headache, leg pains, nausea, vomiting, and cramping. Primary dysmenorrhea is caused by the endocrine system's release of excessive amounts of prostaglandins (prostaglandin); these are hormonelike substances that stimulate the uterus to contract, thus causing the familiar cramps of the disorder. Drugs that block prostaglandin formation can decrease the severity of uterine contractions and can eliminate pain for many women with dysmenorrhea.

Secondary dysmenorrhea is much less common. It can be caused by genital obstructions, pelvic inflammation or degeneration, abnormal uterine wall separation or development (i.e., endometriosis), chronic infection of the uterus, polyps or tumours (tumour), or weakness of the muscles that support the uterus. Often the pain is dull, aching, and persistent. Tumours produce sharper pains. Treatment is directed toward the underlying disorder.