Another name for Letrozole is Femara. My daughter took it until her endo decided that she wasn’t going to grow anymore. She only took it about one year along with flutamide, an androgen blocker, due to raging hormone levels. We could tell a difference almost right away, but once he took her off the femara, she hormones began to rise again. Because of side effect, they don’t want to leave them on them once they’re through growing. If I remember correctly, osteoporosis is the main side effect.