Effects of Letrozole Compared with Danazol on Patients with Confirmed Endometriosis: A Randomized Clinical Trial

Document Type : Original Article


1 Obstetric and Gynecology Department, Isfahan University of Medical Sciences, Isfahan, Iran

2 Isfahan University of Medical Sciences, Isfahan, Iran


Letrozole is an aromatase inhibitor which can decrease estrogen production in peripheral tissues and endometriosis. Danazol, as an androgen, inhibits estrogen production in ovaries and recently has been introduced as an aromatase inhibitor. This study was designed to compare the effects of Danazol with Letrozole on endometriosis symptom relief.

Materials and methods
This study was a randomized clinical trial in which 105 patients with confirmed endometriosis were randomly assigned to one of three groups. Group 1 received Letrozole tablets (2.5 mg/day), calcium (1000 mg/day) and vitamin D (800 IU/day). Group 2 received Danazol tablets (600 mg/day), calcium (1000 mg/day) and vitamin D (800 IU/day). Group 3 (placebo group) were assigned to take two calcium tablets daily (500 mg/tablet) and vitamin D (800 IU/day). Pelvic pain, dysmenorrhea and dyspareunia were assessed in participants at baseline and monthly during the study for a total of six months. Data were analyzed via SPSS version 15 software with Freidman and Wilcoxon tests.

Mean age in three groups has no significant difference. Of the 105 participants who were enrolled in this study, 38 patients were assigned to group 1 (Letrozole group), 37 patients in group 2 (Danazol group) and 31 patients were placed in group 3 (placebo group). This study showed that the mean scores for chronic pelvic pain, dysmenorrhea and dyspareunia for the Letrozole group were less than the Danazol and placebo groups.

This study showed that Letrozole can be more effective than Danazol for reducing chronic pelvic pain, dyspareunia and dysmenorrhea in patients suffering from recurrent endometriosis (Registeration Number: IRCT138812043414N1).