Femara works by preventing the adrenal glands from producing estrogen. They only produce a little bit but for me , as my 1st and 2nd bc were estrogen fed., it helps this. As I had my ovaries removed years ago this kicks me into menopause symptons again. It did thin my hair, removed my sex drive and makes my joints and bones hurt.you need a really good lubricant for sex. It essentially dries everything out. My doctor says , I have to live with it or get off it. Also I have extreme fatigue.