I started taking tamoxifen at age 81 and battled headaches for 12 months until I simplified my life, and they are now minimal. I was told by a pre-menopausal female to stay on the Mylan brand to avoid night sweats and hot flashes which I have done. I will take this drug until the end of my life and feel a certain sense of security in knowing that it prevents the cancer cells from feeding on estrogen. It's partially mind over matter. Good luck to you!