I have been on Anastrozole for over 16 months. At first the side effects were difficult. However, over time, the side effects have receded and other than occasional constipation (usually because I didn't drink enough) and fatigue on some days, there are no longer any noticeable side effects. I will be using them for 5 years more. There are several aromatase inhibitors and if one doesn't work, there are others to try. You may do well on one while another is a horror show. It's not unusual to switch, doctors are used to dealing with making you the most comfortable that they can. I would suggest trying it before deciding against it. Many people have very few side effects on the right one.