You should not use  flecainide if you have a serious heart condition such as bundle branch block or AV block (without a pacemaker), or if your heart cannot pump blood properly.
You may receive your first dose in a hospital or clinic setting to quickly treat any serious side effects.
Before taking this medicine
You should not use flecainide if you are allergic to it, or if:
you have a serious heart condition such as bundle branch block or AV block (unless you have a pacemaker); or
your heart cannot pump blood properly.
Tell your doctor if you have ever had:
a heart attack;
chronic atrial fibrillation, or "AFib";
congestive heart failure;
a heart condition called "sick sinus syndrome";
an electrolyte imbalance (such as low levels of potassium or magnesium in your blood); or
liver disease.
It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.
It may not be safe to breast-feed while using this medicine. Ask your doctor about any risk.
How should I take flecainide?
Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.
You may receive your first few doses in a hospital or clinic setting to quickly treat any serious side effects.
Your heart rate will be monitored using an electrocardiograph or ECG (sometimes called an EKG). This will help your doctor determine how long to treat you with flecainide.
You may also need frequent blood tests to check your liver or kidney function.
Store at room temperature away from moisture, heat, and light.
What happens if I miss a dose?
Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
Overdose symptoms may include nausea, vomiting, slow heart rate, fainting, or seizure (convulsions).
