... stop I was taking 50 mg of Metoprolol succinate ER everyother day for a couple of weeks and have been really lightheaded and dizzy; my doctor said it was probably a side effect of the med. so she stopped it. I also started taking Prednisone 4o mg per day about the same time. I am down to 20 mg of that now. I last took the metoprolol 2 days ago. Still feeling the same.