Does propranolol (beta blockers) cause any long term damage to the heart or anywhere? and are there dangers to taking the medication in general?

Beta-blockers have been around for a long time and, in general, are very safe. The real danger is in making your blood pressure or heart rate decrease too much and give symptoms like lightheadedness. You don’t indicate why you are taking this medicine or if you are taking it all the time. So, if you have continued concerns, talk to your doctor who knows these details. Good luck!