Has anyone tried Arimidex? Worried about side effects starting soon

Any familiar with Arimidex aka anastrozole? I'm not sure if they are really giving me the name brand Arimidex or just saying that instead of Anastrozole but either way the side effects aren't looking so good? They want to start me in 2 weeks and are giving me a break after finishing radiation. They wanted me to take Arimidex and Verzenio at the same time and said then how will I know which one is causing which side effect? I said I'll try Arimidex first only. It seems like all these aromatase inhibitors are hit or miss with side effects!