Digoxin is derived from the leaves of a digitalis plant. Digoxin helps make the heart beat stronger and with a more regular rhythm. Important information You should not use digoxin if you have ventricular fibrillation (a heart rhythm disorder of the ventricles, or lower chambers of the heart that allow blood to flow out of the heart). What happens if I miss a dose? Take the missed dose as soon as you remember. Skip the missed dose if your next dose is less than 12 hours away. Do not take extra medicine to make up the missed dose.