Primary dysmenorrhea is menstrual pain associated with menstrual cycles in the absence of pathologic findings. Pain usually begins within 1–2 years after the menarche and may become progressively more severe. The frequency of cases increases up to age 20 and then decreases with both increasing age and parity. Fifty to 75% of women are affected by dysmenorrhea at some time and 5–6% have incapacitating pain.
Primary dysmenorrhea is low, midline, wave-like, cramping pelvic pain often radiating to the back or inner thighs. Cramps may last for 1 or more days and may be associated with nausea, diarrhea, headache, and flushing. The pain is produced by uterine vasoconstriction, anoxia, and sustained contractions mediated by prostaglandins. The pelvic examination is normal between menses; examination during menses may produce discomfort, but there are no pathologic findings.
NSAIDs (ibuprofen, ketoprofen, mefenamic acid, naproxen) and the cyclooxygenase (COX)-2 inhibitor celecoxib are generally helpful. The medication should be started 1–2 days before expected menses.
Symptoms can be suppressed with use of combined oral contraceptives, DMPA, etonogestrel subdermal (Nexplanon), or the LNG-IUD. Continuous use of oral contraceptives can be used to suppress menstruation completely and prevent dysmenorrhea.
For women who do not wish to use hormonal contraception, other therapies that have shown at least some benefit include local heat; thiamine, 100 mg/day orally; vitamin E, 200 units/day orally from 2 days prior to and for the first 3 days of menses; and high-frequency transcutaneous electrical nerve stimulation.