Fempro 2.5 mg contains the active ingredient letrozole, an aromatase inhibitor used to treat hormone receptor-positive breast cancer in postmenopausal women. By blocking the enzyme aromatase, letrozole reduces the production of estrogen, thereby slowing or halting the growth of cancer cells. Additionally, Fempro 2.5 mg may be prescribed off-label for other hormone-related conditions, such as infertility due to polycystic ovary syndrome (PCOS) or endometriosis.