Hi @anjalima - I'm not sure about bone pain and Kisqali. I started taking Kisqali and Letrozole two weeks apart so that makes it hard sometimes to know which med is causing which symptoms except to compare to the list of possible side effects. I first took Kisqali 600 mg and it gave me the very dangerous heart rhythm that only 4% of people taking it get. So we had to stop, wait a couple weeks for my heart to return to normal and now I take 400 mg. I don't have the dangerous heart rhythm, but it is causing paroxysmal afib that I probably get about once a week for about 12-24 hours. It also causes a lot of fatigue. The fatigue with 600 was really severe. With 400 I run out of energy quickly, but can do what I need to do. Letrozole also causes fatigue. And two months after I started on those two meds, I started taking monthly Octreotide injections for unrelated Lung NETS (neuroendocrine cancer)/DIPNECH and that also causes fatigue, diabetes and a host of problems for me. Kisqali and Octreotide both cause my blood pressure and heart rate to be too low. Then lots of other just annoying stuff but tolerable like hair thinning -- all three meds. Not balding, but I wear hats all the time now. I had very thick hair. I had a toxic sun reaction for a few months and couldn't be in the sun for even two minutes without getting burning and a very itchy rash for a month. The dermatologist felt that was the Letrozole, but that issue stopped. Every med affects each person differently so you may not have any real issues with it. Best of luck with your decision and treatment. Zebra