I stopped taking it because it was driving my heart nuts, I mean I was having these episodes of skipped beats every other minute where before it was about twice a week. I switched to a calcium channel blocker, cardizem without slowly going off of toprol. I didn't have the symptoms until after about 5 weeks of taking the toprol, and I'm not sure if it was from dropping it or taking magnesium that stopped the arrythmia. Perhaps you didn't allow it enough time to actually start working for you.