Key takeaways
Quinidine and flecainide are both prescription medications used to treat abnormal heart rhythms. They work by blocking sodium channels to help normalize your heart's electrical activity. Quinidine is available as generic quinidine sulfate and quinidine gluconate extended-release tablets. Flecainide is also available as a lower-cost generic. Quinidine is used for treating and preventing atrial fibrillation and atrial flutter as well as preventing ventricular arrhythmias, but it is not commonly used today because of better alternatives. Flecainide is used for preventing paroxysmal supraventricular tachycardias, paroxysmal atrial fibrillation/flutter, and ventricular arrhythmias. Quinidine is typically taken every 6 to 12 hours, while flecainide is taken twice a day. Common side effects of quinidine include diarrhea and upset stomach, whereas flecainide can cause dizziness and changes in vision. Both medications many important drug interactions, so be sure to inform your prescriber and pharmacist about all the medications you are taking.
