Yes, generally speaking Tomoxifin has been mostly used for premenopausal women. I’m 65 and post menopausal. My doctor switched me to tomoxifin from Anastrozole last spring when I broke out in severe hives. She said hives can be a rare allergic reaction to Anastrozole. I don’t like either one... for me both have some nasty side effects. But I suppose the side effects are better than cancer!