Cardiac glycosides are medicines that can help the heart beat slower and stronger, which helps the heart pump more blood with each beat. Cardiac glycosides are used to treat heart failure and may also be used to treat irregular rapid heartbeats in the upper heart chamber (atrial fibrillation).

An example of a cardiac glycoside is digoxin (such as Lanoxicaps, Lanoxin).

High levels of a cardiac glycoside in the bloodstream can slow the heart rate below normal (bradycardia). This is most likely to occur in people who are receiving medicine to help reduce water retention (water pills or diuretics), especially those with decreased kidney function.