@karenb I went through the gamut as well. Was started on anastrozole and couldn't handle the side effects similar to what you are experiencing plus head-splitting headaches 24/7. Took a 3-week break and then went on letrozole. Still side effects, but no headaches, dizziness, or brain flog. If one doesn't work, maybe speak with your oncologist and see about a change. All the best to you.