I take xanax also. It doesn't make my heart rate go down, but it helps me to not worry about it. I take .25mg once or twice a day. I don't really notice any side effects from my beta blocker, but my heart rate sometimes drops to the 40s which I hate! I am not usually symptomatic when that happens so my cardiologist says it is OK. I do, sometimes, get tired. I take a very low dose of bisoprolol. I tried atenolol and I couldn't even function because my blood pressure dropped too low. I was out of work for two days. Every medicine is different for everyone, though, so you will just have to find one that works for you. I wish I didn't have to take the beta blockers at all, but I can't stand the tachycardia.