By Medically reviewed by hellodoktor

Generic Name: Flecainide Brand Name(s): Generics only. No brands available.


What is Flecainide used for?

Flecainide is commonly used to treat certain types of serious (possibly fatal) irregular heartbeat (such as persistent ventricular tachycardia and paroxysmal supraventricular tachycardia). It is used to restore normal heart rhythm and maintain a regular, steady heartbeat. It is also used to prevent certain types of irregular heartbeat from returning (such as atrial fibrillation). Flecainide is known as an anti-arrhythmic drug. It works by blocking certain electrical signals in the heart that can cause an irregular heartbeat. Treating an irregular heartbeat can decrease the risk for blood clots, and this effect can reduce your risk of heart attack or stroke.

Older adults should discuss the risks and benefits of this medication with their doctor or pharmacist, as well as other effective and possibly safer treatments.

How should I take Flecainide?

Take this medication by mouth with or without food, usually twice daily or as directed by your doctor.

Dosage is based on your age, kidney and liver function, medical condition, other medications you may be taking, and response to treatment.

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same times each day.

Tell your doctor if your condition does not improve or if it worsens.

How do I store Flecainide?

Flecainide is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store Flecainide in the bathroom or the freezer. There may be different brands of Flecainide that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush Flecainide down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using Flecainide?

Before taking flecainide, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney problems, liver problems, other heart problems (such as previous heart attack, heart pacemaker).

This drug may make you dizzy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.

Flecainide may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.

The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using flecainide, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).

Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/”water pills”) or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using flecainide safely.

Older adults may be more sensitive to the side effects of this drug, especially QT prolongation.

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

This medication passes into breast milk. However, this drug is unlikely to harm a nursing infant. Consult your doctor before breast-feeding.

Is it safe during pregnancy or breast-feeding?

There are no adequate studies in women for determining risk when using this Flecainide during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking Flecainide. Flecainide is pregnancy risk category C according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk,
  • B=No risk in some studies,
  • C=There may be some risk,
  • D=Positive evidence of risk,
  • X=Contraindicated,
  • N=Unknown

Side effects

What side effects can occur from Flecainide?

Dizziness, vision problems (such as blurred vision, problems focusing, seeing spots), shortness of breath, headache, nausea, shaking, tiredness, or weakness may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if any of these unlikely but serious side effects occur: new or worsening symptoms of heart failure (such as ankle/leg swelling, increased tiredness, increased shortness of breath when lying down).

Seek immediate medical attention if any of these rare but serious side effects occur: faster/more irregular heartbeat, severe dizziness, fainting.

A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.


What drugs may interact with Flecainide?

Many drugs besides flecainide may affect the heart rhythm (QT prolongation), including amiodarone, dofetilide, pimozide, procainamide, quinidine, sotalol, and macrolide antibiotics (such as erythromycin), among others. (See also Precautions section.)

Other medications can affect the removal of flecainide from your body, which may affect how flecainide works. Examples include asunaprevir, cimetidine, fluconazole, certain HIV protease inhibitors (such as ritonavir, tipranavir), anti-seizure drugs (such as phenytoin, phenobarbital), among others.

Flecainide may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Does food or alcohol interact with Flecainide?

Flecainide may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Flecainide?

Flecainide may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.


The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using this Flecainide.

What is the dose of Flecainide for an adult?

Usual Adult Dose for Ventricular Tachycardia

Initial dose: 100 mg orally every 12 hours.

Maintenance dose: May be increased in increments of 50 mg bid every 4 days until efficacy is achieved. Most patients with SUSTAINED VT do not require more than 150 mg every 12 hours (300 mg/day), and the maximum dose recommended is 400 mg/day.

Usual Adult Dose for Atrial Fibrillation

Initial dose: 50 mg orally every 12 hours.

Maintenance dose: May be increased in increments of 50 mg bid every 4 days until efficacy is achieved.

Usual Adult Dose for Atrial Flutter

Initial dose: 50 mg orally every 12 hours.

Maintenance dose: May be increased in increments of 50 mg bid every 4 days until efficacy is achieved.

Usual Adult Dose for Wolff-Parkinson-White Syndrome

Initial dose: 50 mg orally every 12 hours.

Maintenance dose: May be increased in increments of 50 mg bid every 4 days until efficacy is achieved.

Usual Adult Dose for Paroxysmal Supraventricular Tachycardia

Initial dose: 50 mg orally every 12 hours.

Maintenance dose: May be increased in increments of 50 mg bid every 4 days until efficacy is achieved.

Renal Dose Adjustments

CrCl=35 mL/min or less: Initial dose: 100 mg orally once a day or 50 mg twice a day. It may take longer than 4 days before a new steady-state plasma level is reached following a dosage change.

In patients with less severe renal dysfunction: Initial dose: 100 mg every 12 hours.

Liver Dose Adjustments

Flecainide should not be used in patients with significant liver dysfunction unless the potential benefits clearly outweigh the risks, as elimination from plasma can be markedly slower in patients with significant hepatic impairment. If it is deemed necessary, frequent and early plasma level monitoring is required to guide dosage and dosage increases should be made very cautiously when plasma levels have plateaued (after more than four days).

Dose Adjustments

Patients not adequately controlled by (or intolerant to) a dose given at 12 hour intervals may be dosed at 8 hour intervals.

Once adequate control of the arrhythmia has been achieved, it may be possible in some patients to reduce the dose as necessary to minimize side effects or effects on conduction. In such patients, efficacy at the lower dose should be evaluated.

Dosing adjustments based on gender may be required. In a pharmacokinetic study involving Japanese patients with supraventricular tachyarrhythmias, nonrenal clearance of flecainide was significantly higher and plasma levels significantly lower in males than in females. Consequently, antiarrhythmic efficacy was significantly lower in males than in females. Japanese male patients may require higher doses in order to achieve therapeutic plasma levels (i.e., approximately 400 ng/mL) of flecainide compared with females.



-This drug should be considered a narrow therapeutic index (NTI) drug as small differences in dose or blood concentrations may lead to serious therapeutic failures or adverse drug reactions.


– Generic substitution should be done cautiously, if at all, as current bioequivalence standards are generally insufficient for NTI drugs.

-Additional and/or more frequent monitoring should be done to ensure receipt of an effective dose while avoiding unnecessary toxicities.

Flecainide should be used cautiously in patients with a history of CHF or myocardial dysfunction.

Electrolyte disturbances (i.e., potassium, sodium) should be corrected before initiating flecainide treatment.


Flecainide is not dialyzable (0%-5%) via hemo- or peritoneal dialysis. A supplemental dose is not necessary.

Other Comments

The maximum recommended dose for patients with PSVT is 300 mg/day.

The maximum recommended dose for patients with Sustained VT is 400 mg/day.

Monitoring of electrolytes (i.e., potassium, sodium) periodically has been recommended in high-risk patients in order to prevent flecainide cardiotoxicity.

What is the dose of Flecainide for a child?

Usual Pediatric Dose for Supraventricular Tachycardia

less than 1 month:

Supraventricular tachycardia: Limited data available: Initial: 2 mg/kg/day orally divided every 12 hours; titrate to clinical response, monitor serum concentration; mean dose required to suppress SVT: 3.35 ± 1.35 mg/kg/day in 17 neonates (n=20 treated neonates; mean PNA: 11.5 days; mean GA: 36.8 weeks; mean birthweight: 2.8 kg); study did not report resultant serum concentrations.

1 month or older:

Initial: 1 to 3 mg/kg/day orally or 50 to 100 mg/m2/day orally in 3 divided doses; usual: 3 to 6 mg/kg/day or 100 to 150 mg/m2/day in 3 divided doses; up to 8 mg/kg/day or 200 mg/m2/day for uncontrolled patients with subtherapeutic levels; higher doses have been reported, however they may be associated with an increased risk of proarrhythmias; a review of world literature reports the average effective dose to be 4 mg/kg/day or 140 mg/m2/day.

How is Flecainide available?

Flecainide is available in the following dosage forms and strengths:

  • Oral Tablet

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of Flecainide, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: February 1, 2018 | Last Modified: September 12, 2019

You might also like