Letrozole is an oral medication that belongs to a class of drugs called aromatase inhibitors. Originally developed to treat hormone-sensitive breast cancer, it is now widely used off-label in fertility treatments to induce ovulation, particularly in individuals with polycystic ovary syndrome (PCOS). Letrozole works by lowering estrogen levels, which triggers the brain to release more follicle-stimulating hormone (FSH), stimulating egg development. It is often used as a first-line alternative to Clomid.