Digoxin, a cardiac glycoside, is indicated for the treatment of various heart diseases including atrial fibrillation, atrial flutter and congestive heart failure. The medication is also used for certain conditions creating rapid/irregular heart beat and sometimes dilated cardiomyopathy. Digoxin, the active ingredient, slows down heart rate and increases heart muscle contraction. The ability of the medication to increase the contraction strength of the heart results in an increase in the amount of blood pumped out of the heart and reduces fluid buildup in the lungs.