A beta blocker reduces the risk of another heart attack for people who have already had one. Most people who take beta blockers do well and have no side effects. But because beta blockers slow your heart, they may make you feel tired. You also may notice that you can't exercise as hard as you used to. For example, you may get out of breath when you take a walk or climb stairs.
Some men can have trouble with erections when they take beta blockers.
Talk to your doctor if you have these problems after you start taking a beta blocker. The beta blocker may make you feel a little dizzy or lightheaded. Because this might happen to you, you shouldn't drive a car or operate dangerous machines until you know if your beta blocker is going to make you feel dizzy. The dizziness usually goes away after you have been taking the medicine for a few days. If you keep feeling dizzy or lightheaded after a few days, tell your doctor.