I was just barely Osteoporotic and my doctor put me on Fosomax. I had no symptoms anything was wrong for 6 months and then developed horrible palpitations! They were so bad I often felt faint. My doctor never suspected the Fosomax but ordered heart tests. All normal . I knew it had to be the Fosomax and stopped taking it and immediately my palpitations lessened. I asked my doctor if the Fosomax caused my palpitations and he said “oh yes, all the bone drugs raise your serum CA levels! Well too much Calcium can affect electrolytes especially magnesium as those two need to stay balanced. It took awhile of taking extra magnesium and no supplemental CA but I recovered a normal heartbeat. I will never take another bone med. I started weightlifting and added Fortibone and gained bone density to osteopenia.