I take Coreg CR 20 mg per day. I have noticed since taking it, my energy level has decreased, but then it seemed to improve, but then I started on Lisinopril and energy level dropped again, then after a month or so improved, then I got sick a lot (have small kids with big mean germs) and my energy level fluctuates, so don't know what to think. All this has occured over about a 4 month period...probalby not long enough to make me any kind of expert.