Toprol-XL Side Effects: September 15, I first started taking Toprol XL 50 mg for an irreg http://www.medications.com/effect/view/23624 September 15, I first started taking Toprol XL 50 mg for an irregular heart 2007 beat. That was about 2.5 years ago. It didn't help me at 1:27 PM first so my Dr. upped it to 100mg. It helped for about a You story sounds a lot like mine. I've been taking this medicati Sat, 22 Sep 2007 11:32:27 -0400 http://www.medications.com/effect/view/23624?item=1980 You story sounds a lot like mine. I've been taking this medication just over two years for an irregular heartbeat, and honestly the side effects are worse than my original problem. Seems some of the side effects come in stages, and for the most part http://www.medications.com/effect/view/23624?item=1980