Progestin-only pills may be a better first-line treatment for endometriosis than combined estrogen-progestin contraceptive pills.

For decades, combined estrogen-progestin oral contraceptive pills (OCPs) have been the first-line treatment for menstrual and pelvic pain associated with endometriosis without any clinical evidence of efficacy. Initial relief provided by OCPs is likely a result of improvement in primary dysmenorrhea. Biologic data and limited clinical evidence support a potential adverse effect of long-term use of OCPs on the progression of endometriosis. In contrast, there is randomized, controlled trial data to support the use of oral progestin-only treatment for pelvic pain associated with endometriosis and for suppressing the anatomic extent of endometriotic lesions. Both norethindrone acetate and dienogest have regulatory approval for treating endometriosis and may be better than OCPs as a first-line therapy.