I was taking Anastrozole for about a year and 8 months but had developed mild carpal tunnel syndrome in both arms, trigger thumb on the left side and something called DeQuervain's tendonitis on my left arm which made it difficult to do much of anything. I had not had any issues until started taking of the Anastrozole. My oncologist said to try Letrozole but this only made things worse, so we agreed to stop for couple months to see if things improved. During the rehab period I did get a corticosteroid shot for the tendonitis as it was quite painful. After a couple months, these issues slowly disappeared so I know it was from the AI meds. When discussing taking Tamoxifen, the oncologist too thought that it may have the same impact so we decided to do 10mg instead of 20 mg hoping the side effects would not be as bad. I have been taking the 10mg for 4 mos now and while I have some of the more common side effects the muscle/joint types are much more bearable so I will stick with it for now. If things should get unbearable in regards to the muscle/joint issues going forward I may just decide to stop these meds but for now I figured something is better than nothing. At least the pains it caused did go away for most part in my case so I was happy about that. But yes, if I had stayed on it I would not be able to do a lot of things with limited use of my arms so this was the best solution for me. So, I do totally understand stopping these meds if they are so debilitating. I too had osteopenia prior to starting these meds so will see in my DEXA scan this year if it has caused more problems. I had been trying to take supplements and exercise with light weights and resistance bands but we'll see if this did anything. Good luck on your journey.