I just started taking Toprol today for tachycardia,increased BP, which my dr says may me hyperthyroidism. I have been waking up at 3 am for days with a racing heart. No racing heart now with Toprol XL 50 mg, but my fingers feel swollen and I can't sleep. I feel short of breath and my muscles hurt. After reading all of the comments, I will call the dr tomorrow and ask for something else. This drug is scary.