Causes. Primary dysmenorrhea results from the release of prostaglandins, or hormones produced by the uterus and cervix, that cause the uterus to contract. It is not yet known what triggers the release of these hormones. The pain may also result from the stretching of the cervix as it expands to allow passage of blood clots from the uterus to the vagina.

Secondary dysmenorrhea may be the result of endometriosis, fibroids, PID, ectopic pregnancy or IUD use. Women who smoke, drink alcohol during their periods, are overweight, or who started menstruating before age 11 have an increased risk of dysmenorrhea. Stress, caffeine and a family history of severe menstrual pain may also increase your risk.

Symptoms. Abdominal pain, which may radiate to the back of your legs or lower back, is the most common symptom of dysmenorrhea.
Symptoms may also include: nausea, diarrhea or vomiting, fatigue, fever, headache and lightheadedness. Pain usually develops within hours of menstruation starting and peaks as the flow becomes heaviest during the first day or two.

Diagnosis. Primary dysmenorrhea is diagnosed if severe pain occurs during menstruation. Dysmenorrhea tends to be most severe in the early teens but lessens with age. Secondary dysmenorrhea generally begins earlier in the menstrual cycle and lasts longer than normal cramps.

Treatment. The first line of treatment is usually medication, such as aspirin or ibuprofen, which inhibits prostaglandin production. These medications are most effective when started 24 to 72 hours before the onset of menstruation. Oral contraceptives that prevent ovulation can also help, as can exercising regularly and applying warm compresses to the abdomen.

In secondary dysmenorrhea, it is important to treat the underlying cause. This may involve more invasive treatments, such as endometrial ablation. (See "Uterine Conditions: Menorrhagia".)