I have been on the metoprolol for years and have not had any problems at all. My dose is 150. It took care of my tachycardia and irregular beats. If I miss it I remember because the beats change. It really made my life much better as I did not have my "funky beats" to worry about. I had heard negative remarks too but none of the side affects happened to me. Yeah! The cardiologist told me it was like a fortress built around my heart to protect it. Even when I do something that raises my heart rate it keeps it from going too high. I hope it works as well for you.