Previous research results on IL-8 and pelvic pain symptoms among those with endometriosis have been mixed, with some studies reporting no associations [25,31,38] and a recent study reporting a positive association between IL-8 and dysmenorrhea, post-menstrual pain, and dyspareunia [32]; however, none of these studies considered the effects of analgesic use on the associations between IL-8 and pelvic pain. Here, CXCL8 is linked to endometriosis.