Flecainide acetate | Side Effects, Dosage, Uses & More
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Generic Name:

flecainide, Oral tablet

All Brands

  • Tambocor (Discontinued)
A discontinued drug is a drug that has been taken off the market due to safety issues, shortage of raw materials, or low market demand.
SECTION 1 of 5

Highlights for flecainide

Oral tablet
1

Flecainide is an oral drug that’s used to prevent the following types of abnormal heart rhythms: paroxysmal supraventricular tachycardia (PSVT), paroxysmal atrial fibrillation or flutter (PAF), and ventricular arrhythmias.

2

Your dosage depends on your age and the condition that you’re treating. Your doctor will decide a dose that’s right for you.

3

If you’ve had a heart attack within the past two years, flecainide may raise your risk of having another heart attack. This can be fatal. This drug should only be used if you have a life-threatening irregular heart rate.

4

Flecainide may cause new or worsened abnormal heart rhythms. Depending on your condition, your doctor may first give you this medication in the hospital so that your heart rhythms can be closely monitored.

5

Common side effects include nausea, constipation, headache, dizziness, and vision changes, such as blurred vision.

IMPORTANT INFORMATION

FDA warning

This drug has a Black Box Warning. This is the most serious warning from the Food and Drug Administration (FDA). A black box warning alerts doctors and patients to potentially dangerous effects.

  • Heart attack warning: If you’ve had a heart attack within the past two years, flecainide may raise your risk of having another heart attack, which can be fatal. This drug should only be used if you have a life-threatening irregular heart rate.
  • Irregular heart rate warning: Tell your doctor if you have atrial fibrillation or atrial flutter. If you have these conditions where your heart does not beat correctly, you have an increased risk for developing certain types of irregular heartbeats. Flecainide is not recommended if you have chronic atrial fibrillation.

Abnormal heart rhythm risk

Flecainide can cause new or worsened abnormal heart rhythms. Depending on your condition, your doctor may first give you this medication in the hospital so that your heart rhythms can be closely monitored.

Heart failure warning

Flecainide can cause or worsen heart failure. Your doctor will closely monitor the levels of this drug in your body if you have heart failure.

What is flecainide?

Flecainide is a prescription drug. It is available as an oral tablet.

Flecainide is available in its generic form. Generic drugs usually cost less. In some cases they may not be available in every strength or form as the brand. Talk to your healthcare provider to see if the generic will work for you.

This drug may be used as part of a combination therapy. That means you need to take it with other drugs.

Why it's used

Flecanide is used to prevent paroxysmal atrial fibrillation, ventricular arrhythmia, and paroxysmal supra ventricular tachycardia.

More Details

How it works

Flecainide belongs to a class of drugs called antiarrhythmics. A class of drugs refers to medications that work similarly.

More Details

Why it's used

Flecanide is used to prevent paroxysmal atrial fibrillation, ventricular arrhythmia, and paroxysmal supra ventricular tachycardia.

Paroxysmal atrial fibrillation is a condition that causes temporary abnormal heart rate in the upper chambers of your heart. It can cause symptoms such as lightheadedness, chest pain, and shortness of breath.

Ventricular arrhythmia is an abnormal heart rhythm that starts in the lower chambers of your heart. Your doctor may give you this drug if they believe that your condition is life threatening.

Supra ventricular tachycardia is a condition that causes a temporary increase in your heart rate that starts in the parts of your heart above the ventricles. It can cause symptoms such as shortness of breath, chest tightness, and being able to feel your heart beating.

How it works

Flecainide belongs to a class of drugs called antiarrhythmics. A class of drugs refers to medications that work similarly. They have a similar chemical structure and are often used to treat similar conditions.

This drug works by slowing down the electrical signals in your heart. This makes your heart rhythm stable.

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SECTION 2 of 5

flecainide Side Effects

Oral tablet

Most Common Side Effects

The most common side effects that occur with flecainide include:

  • stomach problems. Symptoms may include:

    • constipation
    • stomach pain
    • nausea
  • vision problems. Symptoms may include:

    • blurred vision
    • spots in your field of vision
  • low blood pressure. Symptoms may include:

    • dizziness
    • lightheadedness
    • feeling faint or weak
  • uncontrollable shaking of parts of your body, such as your hands, arms, head, or legs

  • headache

Serious Side Effects

If you experience any of these serious side effects, call your doctor right away. If your symptoms are potentially life threatening, or if you think you’re experiencing a medical emergency, call 9-1-1.

  • heart failure. Symptoms may include:

    • a buildup of fluid in your arms, legs, hands, or feet
    • unexplained weight gain
  • abnormal heart rate. Symptoms may include:

    • fluttering heart rate
    • slow heart rate
    • fast heart rate
    • chest pain
    • shortness of breath
  • liver problems. Symptoms may include:

    • yellowing of your skin or the whites of your eyes
    • loss of appetite
    • weakness
  • stomach problems. Symptoms may include:

    • severe abdominal pain
    • loss of appetite
    • severe nausea
  • bleeding issues. Symptoms may include:

    • coughing up blood
    • unexplained bleeding or bruising, or bleeding or bruising that lasts longer than usual
  • severe allergic reaction. Symptoms may include:

    • wheezing
    • chest tightness
    • itching
    • swelling of your face, lips, tongue, or throat
  • flu-like symptoms. Symptoms may include:

    • fever
    • chills
    • headache
    • muscle and joint pains
    • tiredness
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Flecainide doesn’t cause drowsiness.

Mild side effects may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
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flecainide May Interact with Other Medications

Oral tablet

Flecainide can interact with other medications, herbs, or vitamins you might be taking. That’s why your doctor should manage all of your medications carefully. If you’re curious about how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Note: You can reduce your chances of drug interactions by having all of your prescriptions filled at the same pharmacy. That way, a pharmacist can check for possible drug interactions.

Alcohol interaction

Your body processes alcohol and this drug in similar ways. That means that if you drink alcohol, this drug might take longer to leave your body. You may also experience worse side effects.

Medications that might interact with this drug

Digoxin

Flecainide will increase the levels of digoxin in your body, but you shouldn’t have an increased risk of side effects.

Heart and blood pressure drugs

Beta blockers, such as:

  • acebutolol (Sectral)
  • atenolol (Tenormin)
  • bisoprolol (Zebeta)
  • carteolol (Cartrol)
  • esmolol (Brevibloc)
  • metoprolol (Lopressor, Toprol XL)
  • nadolol (Corgard)
  • nebivolol (Bystolic)
  • propranolol (Ineral LA)

Using beta blockers with flecainide will increase the levels of both medications in your body. But you shouldn’t have an increased risk of side effects from either medication.

Verapamil

Using this drug with flecainide is not recommended, because it may slow your heart rate too much.

Disopyramide

Using this drug with flecainide is not recommended, because it may slow your heart rate too much.

Amiodarone

When using this drug with flecainide, your doctor will give you half your normal dose of flecainide and monitor you for side effects. Your doctor must monitor the levels of flecainide in your body before they change your dose.

Human immunodeficiency virus (HIV) medications
  • Protease inhibitors, such as:
    • atazanavir (Reyataz)
    • darunavir (Prezista)
    • fosamprenavir (Lexiva)
    • indinavir (Crixivan)
    • lopinavir and ritonavir (Kaletra)
    • nelfinavir (Viracept)
    • ritonavir (Norvir)
    • saquinavir (Invirase)
    • tipranavir (Aptivus)

Using these drugs with flecainide may increase your risk of serious side effects from flecainide. Don’t take protease inhibitors with flecainide.

Medications that make urine acidic

Examples are:

  • ammonium chloride
  • ascorbic acid

Using these drugs with flecainide will lower the effectiveness of flecainide in your body. This means that it won’t work as well.

Medications that make urine basic

Examples are:

  • sodium bicarbonate
  • potassium citrate
  • sodium citrate
  • acetazolamide
  • methazolamide

Using these drugs with flecainide will increase levels of flecainide in your body. This may increase your risk of side effects.

Heartburn medication
  • cimetidine

This drug will increase the levels of flecainide in your body. This may increase your risk of side effects.

Breast cancer medication
  • toremifene

Using this drug with flecainide may increase your risk of life-threatening abnormal heart rhythms. Use caution when taking these drugs together. Your doctor will need to monitor your heart rhythm.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.
Flecainide warnings
heart attack
People with a heart attack in the last 2 years

If you’ve had a heart attack within the past two years, flecainide may raise your risk of having another heart attack, which can be fatal. This drug should only be used if you have a life-threatening irregular heart rate.

atrial fibrillation
People with chronic atrial fibrillation/flutter

Tell your doctor if you have atrial fibrillation or atrial flutter. If you have these conditions where your heart doesn’t beat correctly, you have an increased risk for developing certain types of irregular heartbeats. Flecainide is not recommended if you have chronic atrial fibrillation.

abnormal heart rhythm
People with abnormal heart rhythm

Flecainide may cause new or worsened abnormal heart rhythms. Depending on your condition, your doctor may first give you this medication in the hospital so that your heart rhythms can be closely monitored.

sick sinus syndrome
People with sick sinus syndrome

This medication can make your condition worse. If you have sick sinus syndrome, this medication may slow down or stop your heart from beating. Use Flecainide with extreme caution if you have sick sinus syndrome.

heart failure
People with heart failure

Flecainide may cause or worsen heart failure. Your doctor will closely monitor the levels of this drug in your body if you have heart failure.

cardiac conduction abnormalities
People with cardiac conduction abnormalities

Flecainide works by slowing the electrical signals in your heart. If the levels of medication are too high in your body, it can slow the signaling of your heart too much and lead to an increased risk of side effects.

low potassium levels
People with high or low potassium levels

Having too much or not enough potassium in your body can affect how well flecainide works. Your doctor will do a blood test to make sure that you have normal potassium levels before you start taking flecainide.

pacemakers
People with pacemakers or pacing electrodes

Flecainide should be used with caution if you have a permanent pacemaker or temporary pacing electrodes. This drug can lower the effect of these devices on controlling your heart rhythm.

urine pH
People with changes in urine pH

The pH level of your urine (basic or acidic) can increase or decrease the levels of the medication in your body. These changes can either increase your risk of side effects or lower the effect of the medication. Your doctor will do a simple urine test to check the pH level of your urine.

liver problems
People with liver problems

Don’t take this drug if you have liver problems unless your doctor says that it’s OK. If your doctor starts you on flecainide, the levels of the medication in your body will be monitored regularly before your doctor changes your dose.

pregnant women
Pregnant women

Flecainide is a category C pregnancy drug. That means two things:

  1. Research in animals has shown adverse effects to the fetus when the mother takes the drug.
  2. There haven’t been enough studies done in humans to be certain how the drug might affect the fetus.

Tell your doctor if you’re pregnant or plan to become pregnant. Flecainide should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. 

breastfeeding
Women who are breast-feeding

Flecainide passes through breast milk and can cause serious side effects in your child.

You and your doctor may need to decide if you’ll take flecainide or breastfeed.

seniors
For seniors

Antiarrhythmic drugs, such as flecainide, shouldn’t be the first medications used to treat atrial fibrillation in people over the age of 65.

These medications have more side effects in people over the age of 65 than other drugs for atrial fibrillation.

children
For children

The safety and effectiveness of flecainide haven’t been established for use in people younger than 18 years old.

allergies
Allergies

Flecainide may cause a severe allergic reaction. Symptoms may include:

  • trouble breathing
  • swelling of your throat or tongue
  • hives

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal.

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How to Take flecainide (Dosage)

Oral tablet

All possible dosages and forms may not be included here. Your dose, form, and how often you take it will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

Prevention of paroxysmal atrial fibrillation or flutter (PAF)
Form: Oral tablet
Strengths: 50 mg, 100 mg, and 150 mg
Adult dosage (ages 18-64 years)
  • Starting dose:
    • 50 mg taken every 12 hours
  • Dose changes:
    • Your doctor may increase your dose by 50 mg taken twice per day every 4 days until the drug is effective.
Child dosage (ages 0-17 years)

The safety and effectiveness of flecainide have not been established for use in people younger than 18 years old.

Senior dosage (ages 65 years and older)

Your body may process this drug more slowly. Your doctor may start you on a lowered dose so that too much of this drug doesn’t build up in your body. Too much of the drug in your body can be toxic.

Special considerations

Kidney problems:

  • Severe kidney disease: 100 mg taken once per day (or 50 mg taken twice per day). The levels of flecainide in your body must be monitored before any dose changes.
  • Mild and moderate kidney disease: Dose reduction isn’t required if you have mild or moderate kidney disease. However, dose changes shouldn’t be made more often than every 5 days or more. The levels of flecainide in your body must be monitored before any dose changes.

Liver problems: Flecainide shouldn’t be used in people with liver problems unless your doctor decides that it’s OK. If your doctor starts you on flecainide, the levels of the medication in your body must be monitored before any dose changes.

People who also take amiodarone: If you’re taking amiodarone with flecainide, your doctor will give you half of your normal dose of flecainide and watch you for side effects. Your doctor must monitor the levels of flecainide in your body regularly before any dose changes.

Prevention of ventricular arrhythmias
Form: Oral tablet
Strengths: 50 mg, 100 mg, and 150 mg
Adult dosage (ages 18-64 years)
  • Starting dose:
    • 100 mg taken every 12 hours
  • Dose changes:
    • Your doctor may increase your dose by 50 mg taken twice per day every 4 days until the drug is effective. Most people don’t need doses higher than 150 mg taken every 12 hours. The maximum dose is 400 mg per day.
Child dosage (ages 0-17 years)

The safety and effectiveness of flecainide have not been established for use in people younger than 18 years old.

Senior dosage (ages 65 years and older)

Your body may process this drug more slowly. Your doctor may start you on a lowered dose so that too much of this drug doesn’t build up in your body. Too much of the drug in your body can be toxic.

Special considerations

Kidney problems:

  • Severe kidney disease: 100 mg taken once per day (or 50 mg taken twice per day). The levels of flecainide in your body must be monitored before any dose changes.
  • Mild and moderate kidney disease: Dose reduction isn’t required if you have mild or moderate kidney disease. However, dose changes shouldn’t be made more often than every 5 days or more. The levels of flecainide in your body must be monitored before any dose changes.

Liver problems: Flecainide shouldn’t be used in people with liver problems unless your doctor decides that it’s OK. If your doctor starts you on flecainide, the levels of the medication in your body must be monitored before any dose changes.

People who also take amiodarone: If you’re taking amiodarone with flecainide, your doctor will give you half of your normal dose of flecainide and watch you for side effects. Your doctor must monitor the levels of flecainide in your body regularly before any dose changes.

Prevention of paroxysmal supraventricular tachycardia (PSVT)
Form: Oral tablet
Strengths: 50 mg, 100 mg, and 150 mg
Adult dosage (ages 18-64 years)
  • Starting dose:
    • 50 mg taken every 12 hours
  • Dose changes:
    • Your doctor may increase your dose by 50 mg taken twice per day every 4 days until the drug is effective. The maximum dose is 300 mg per day.
Child dosage (ages 0-17 years)

The safety and effectiveness of flecainide have not been established for use in people younger than 18 years old.

Senior dosage (ages 65 years and older)

Your body may process this drug more slowly. Your doctor may start you on a lowered dose so that too much of this drug doesn’t build up in your body. Too much of the drug in your body can be toxic.

Special considerations

Kidney problems:

  • Severe kidney disease: 100 mg taken once per day (or 50 mg taken twice per day). The levels of flecainide in your body must be monitored before any dose changes.
  • Mild and moderate kidney disease: Dose reduction isn’t required if you have mild or moderate kidney disease. However, dose changes shouldn’t be made more often than every 5 days or more. The levels of flecainide in your body must be monitored before any dose changes.

Liver problems: Flecainide shouldn’t be used in people with liver problems unless your doctor decides that it’s OK. If your doctor starts you on flecainide, the levels of the medication in your body must be monitored before any dose changes.

People who also take amiodarone: If you’re taking amiodarone with flecainide, your doctor will give you half of your normal dose of flecainide and watch you for side effects. Your doctor must monitor the levels of flecainide in your body regularly before any dose changes.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Healthline Pharmacist Editorial Team

If you don't take it at all

The symptoms of your abnormal heart rhythm may not improve or may get worse.

If you stop taking it suddenly

If your condition got better while you were taking the medication and you stop taking flecainide suddenly, your abnormal heart rhythm may come back.

If you don't take it on schedule

You may not see a full benefit of this medication for the treatment of your abnormal heart rhythm. If you double up your dose or take it too close to your next scheduled time, you may be at higher risk of serious side effects.

What to do if you miss a dose

If you forget to take your dose, take it as soon as you remember. If it’s just a few hours before the time to take your next dose, then only take one dose at that time.

Never try to catch up by taking two doses at once. This could result in toxic side effects.

How to tell if the drug is working

Paroxysmal atrial fibrillation prevention—You may be able to tell if this medication is working if your symptoms of lightheadedness, chest pain, and shortness of breath improve.

Ventricular arrhythmia prevention—You may be able to tell if this medication is working if your symptoms of fainting, chest pain, shortness of breath, or fast heart rate improve.

Paroxysmal supraventricula tachycardia prevention—You may be able to tell if this medication is working if your symptoms of shortness of breath, chest tightness, and being able to feel your heart beating improve.

Flecainide is a long-term drug treatment.

Important considerations for taking flecainide
can cut tablet
You can cut or crush the tablet
storage
Store flecainide at room temperature
See Details
refillable
Prescription is refillable
travel
Travel
See Details
Clinical Monitoring
Clinical monitoring
See Details
not usually stocked
Not every pharmacy stocks this drug, so call ahead
prior authorization required
Insurance
See Details

Store flecainide at room temperature

Keep in temperatures from 59–86°F (15--30°C).

Don’t freeze flecainide.

Keep the drug away from light and high temperatures.

Keep your drugs away from areas where they could get wet, such as bathrooms. Store this drug away from moisture and damp locations.

Travel

When traveling with your medication:

  • Always carry your medication with you or in your carry-on bag.
  • Don’t worry about airport X-ray machines. They can’t hurt this medication.
  • You may need to show your pharmacy’s label to clearly identify the medication. Keep the original prescription label with you when traveling.
  • Don’t leave this medicine in the car, especially when the temperature is hot or freezing.

Clinical monitoring

During your treatment with flecainide, your doctor will monitor the level of the drug in your body. This should be monitored regularly because your risk of side effects increases if your flecainide levels are too high. Your levels should be monitored more closely if you have severe kidney disease, severe liver disease, or congestive heart failure.

Insurance

Many insurance companies will require a prior authorization before they approve the prescription and pay for flecainide.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be more suitable for you than others. Talk to your doctor about possible alternatives.

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How Much Does flecainide Cost?

Oral tablet

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Lowest price for flecainide

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Safeway $32.25
Kroger Pharmacy $32.75
These prices represent the lowest priced national pharmacies for flecainide on GoodRx. They may be lower than your insurance.

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These prices represent the lowest priced national pharmacies for flecainide on GoodRx. They may be lower than your insurance.

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Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on June 25, 2015

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
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