Leuprolide is used for prostate cancer, endometriosis, Uterine fibroids, precocious puberty and female infertility. It is also used to reduce the thickness of the endometrium of the uterus in preparation for surgery. Leuprolide reduces the amount of sex hormones (testosterone in men and estrogen in women). It works by decreasing the blood levels of testosterone in males. Leuprolide also acts by shutting off hormones made by the ovaries (female reproductive organs), so the estrogen (one of the hormones that causes females to have periods) level is lowered.