Flecainide (oral)

Flecainide is prescribed for patients with arrhythmias (irregular heartbeats) to help maintain the heart rhythm.


Flecainide is a prescription drug that treats arrhythmias (irregular heartbeats) like paroxysmal atrial fibrillation/flutter and paroxysmal supraventricular tachycardia. This medication is an antiarrhythmic and can also counteract sustained ventricular tachycardia. It directly improves the heart tissue and will reduce the speed of nerve impulses within the heart. These actions aid in maintaining the heart rhythm.

Occasionally, flecainide can trigger new heart rhythm issues or can cause existing heart rhythm issues to become worse. Due to the potential to trigger serious issues for certain patients, flecainide is only utilized to treat severe heart rhythm issues. Discuss this potential effect with your physician.

Flecainide can only be obtained with a valid prescription from your doctor.

This medication is available in:

  • Tablet
  • Extended release capsules

Flecainide is manufactured under the US brand name Tambocor.

Condition treated

  • Arrhythmia

Type of medicine

  • Antiarrhythmics

Side Effects

In addition to the necessary benefits of flecainide, this medication can also trigger side effects that may be undesirable. While it is highly unlikely that every side effect may take place, if they do happen they could require medical care.

Consult with your physician right away if you encounter any of the subsequent side effects:

More Common Side Effects (Medical Care Required)

  • Wheezing
  • Pulse pounding, fast, racing, or irregularity
  • Lightheadedness, fainting, or dizziness
  • Labored or difficulty breathing
  • Heartbeat pounding, fast, racing, or irregularity
  • Chest tightness
  • Breath shortness

Less Common Side Effects (Medical Care Required)

  • Unsteady or shaky walk
  • Trembling, unsteadiness, or other issues with coordination or muscle control
  • Swelling of the lower legs or feet
  • Sweating increase
  • Slight or partial paralysis
  • Shaking or trembling of the feet or hands
  • Shakiness of the feet, hands, arms, or legs
  • Sensations of warmth
  • Redness of the arms, neck, face, or upper chest (occasional)
  • Numbness, itching, tingling, crawling, prickling, or burning feelings
  • Fever
  • Fainting
  • Chest pain

Rare Side Effects (Medical Care Required)

  • Yellow skin or eyes
  • White spots, ulcers, or sores in mouth or on lips
  • Weakness or tiredness (unusual)
  • Urine passing difficulty (dribbling)
  • Urine dilute or pale (increased)
  • Urination frequency
  • Swollen glands
  • Sweating
  • Stools that are tarry (black)
  • Stabbing pain
  • Sore throat
  • Pins and needles sensations
  • Pinpoint areas on skin (red)
  • Nervousness
  • Nausea
  • Loud breathing
  • Lightheadedness, faintness, or dizziness when rising quickly from a sitting or lying position
  • Jaw, back, or arm pain
  • Headache
  • General sensations of illness or discomfort
  • Fast or slow heartbeat
  • Ear pounding
  • Difficulty breathing
  • Difficult or painful urination
  • Decrease in urination volume
  • Decrease in urination frequency
  • Cough
  • Convulsions
  • Confusion
  • Chills
  • Chest heaviness or tightness
  • Chest discomfort
  • Bruising or bleeding (unusual)
  • Bronchial secretion thickened
  • Breathing difficulty
  • Blurred vision
  • Bleeding of the gums

Certain side effects may take place but do not always require medical care. These specific side effects may diminish throughout the course of treatment as the body of the patient becomes more adjusted to the medication. In addition, your physician can inform you of additional methods of reducing or preventing certain side effects. Consult with your medical care professional if you encounter any of the subsequent side effects, if they become troublesome, prolonged, or simply if you have questions or concerns regarding them.

More Common Side Effects (Medical Care Not Required)

  • Vision blurred (spots in vision)

Less Common Side Effects (Medical Care Not Required)

  • Weight loss
  • Stomach pain, discomfort, or upset
  • Stomach or abdominal pain
  • Stomach acidity or sour sensations
  • Spinning sensations
  • Sleeping difficulty or inability
  • Skin rash
  • Sensation of constant movement when it is not actually taking place (movement of either surroundings or self)
  • Mental depression or anxiety
  • Loss or lack of strength
  • Indigestion
  • Heartburn
  • Hearing loss
  • General sensation of illness or discomfort
  • Drowsiness or sleepiness (unusual)
  • Diarrhea
  • Depression
  • Constipation
  • Buzzing, ringing, or additional types of noise within the ears (unexplained)
  • Belching
  • Appetite loss

Rare Side Effects (Medical Care Not Required)

  • Welts or hives
  • Unusual or false feelings of well-being
  • Unrestrained movements of the eye
  • Trouble seeing in the dark
  • Too much gas or air in the intestines or stomach
  • Thinning of the hair or hair loss
  • Taste changes
  • Swelling of the tongue, mouth, or lips
  • Skin swollen or red
  • Skin scaly
  • Skin itchiness
  • Skin cracks
  • Shifts in the way you perceive color
  • Sensations of illusoriness
  • Sensation of detachment from body or self
  • Reduced responsiveness or awareness
  • Passing gas
  • Muscle stiffness or pain
  • Muscle cramping or aching
  • Memory loss
  • Memory issues
  • Loss of emotion or feeling
  • Loss in sexual performance, drive, desire, or ability
  • Less interest in sexual encounters
  • Joint swelling
  • Joint pain
  • Heightened sensitivity to sunlight (the eyes)
  • Feeling full
  • Failure to keep or have an erection
  • Eye irritation or pain
  • Extreme sleepiness
  • Dry mouth
  • Difficulty moving
  • Bodily heat loss
  • Bloating

It is important to note that additional side effects not included in the previous lists could take place for certain patients. If other side effects are observed, always consult with your physician.

Consult with your doctor for any medical recommendations they may have regarding side effects. The FDA also accepts side effect reports, they can be reached by calling 1-800-FDA-1088.


In certain circumstances, the first dose of this medication will be administered within a hospital setting. Your physician will monitor your condition carefully after this medication is taken to ensure that no severe side effects take place. This medication must be taken precisely as recommended by your physician despite the fact that you may feel better. Never take more medication than prescribed by your doctor.

This medication can be taken with food or without.

This medication is the most effective when patients always have an amount of the medication within the bloodstream. To aid in maintaining the amount of medication, try to never miss a dose. In addition, it is optimal to take each dose 12 hours after the last, once during the night and once in the morning, unless suggested otherwise by your physician. For help on planning the most optimal dosage times, ask your doctor.

For infants and babies who drink a great deal of milk and are under 2, the physician may change the dosage information when they begin drinking less milk or if gastroenteritis takes place. Consult with your physician if you have concerns or questions regarding this.

This medication has an extended half-life (for patients, it is 12 ' 27 hours). Patients with normal hepatic and renal function may not reach steady plasma levels until they have been taking flecainide for three to five days. Dosage increases should not take place more often than one time after four hours. This is because the necessary dose may not be reached in the initial two to three days of treatment.

Dosing Instructions

Different patients will be given a different prescription of this medication. Always follow the instructions given by your physician, or the instructions on the medication container label. The information listed below only includes general doses of flecainide. Do not adjust your dose if your prescribed dose differs from this information unless instructed by your doctor.

The dose you are given depends on how strong the medication is. In addition, how many doses are taken per day, the duration allotted from one dose to another, and the total duration for which flecainide is being taken will depend on the unique medical issue for which you need the medication.

Tablet Dosing Information (Oral Form)

 Adults: Initially, take 50 milligrams once per 12-hour period. Your physician may adjust your prescribed dose as required.

 Children: A physician must determine the dose depending on your child's unique needs. The dose is determined due to body size and must be calculated by a physician. The preliminary dose is 100 milligrams for each square meter.

  • For sustained ventricular tachycardia:

 Adults: Initially, take 100 milligrams one time for every 12-hour time period. The medical care professionals involved in your medications can increase the dose as you need them to. However, the maximum dose is not typically greater than 400 milligrams each day.

Children: A physician must calculate dosage information. The dose will be either split into two to three doses each day.

Missed Dose

If a dose of flecainide is skipped, ensure that you take it right when you recognize that a dose had been missed. Alternatively, if it is nearer in the dosing schedule to the next dose, the missed dose can remain skipped and you may return to your designated medication schedule. Never take a double dose of flecainide.


Drug Interactions

Some medications should never be taken at the same time. However, in special circumstances two medications can be combined even if there is a chance of interaction. In cases such as these, your physician may be inclined to adjust the dosage information or take other kinds of precautions to protect you. Before taking flecainide, it is imperative that you inform your medical professional if you are already taking any of the medications below. The interactions included here have been chosen due to the possible consequences, and this list is not all-inclusive.

It is not suggested to take any of the medications below with flecainide. Your physician may switch other medications you may be taking that may interact, or they may choose not to prescribe flecainide.

  • Ziprasidone
  • Vernakalant
  • Tipranavir
  • Thioridazine
  • Terfenadine
  • Sparfloxacin
  • Saquinavir
  • Ritonavir
  • Piperaquine
  • Pimozide
  • Mesoridazine
  • Levomethadyl
  • Dronedarone
  • Cisapride
  • Bepridil
  • Amisulpride
  • Amifampridine

Taking flecainide with any of the medications below is not typically suggested, but some unique circumstances may require it. If the medications are prescribed simultaneously, your doctor will likely adjust the dose for either medication for your safety.

  • Zuclopenthixol
  • Zotepine
  • Zolmitriptan
  • Voriconazole
  • Vinflunine
  • Vemurafenib
  • Vasopressin
  • Vardenafil
  • Vandetanib
  • Triptorelin
  • Trimipramine
  • Trimethoprim
  • Trifluoperazine
  • Trichlormethiazide
  • Trazodone
  • Toremifene
  • Tizanidine
  • Tetrabenazine
  • Telithromycin
  • Telavancin
  • Telaprevir
  • Tedisamil
  • Tacrolimus
  • Sunitinib
  • Sultopride
  • Sulpiride
  • Sulfamethoxazole
  • Spiramycin
  • Sotalol
  • Sorafenib
  • Solifenacin
  • Sodium Phosphate, Monobasic
  • Sodium Phosphate, Dibasic
  • Sodium Phosphate
  • Simeprevir
  • Sevoflurane
  • Sertraline
  • Sertindole
  • Sematilide
  • Salmeterol
  • Risperidone
  • Ranolazine
  • Quinidine
  • Quetiapine
  • Protriptyline
  • Propafenone
  • Promethazine
  • Prochlorperazine
  • Procainamide
  • Probucol
  • Prilocaine
  • Prajmaline
  • Posaconazole
  • Polythiazide
  • Pitolisant
  • Pirmenol
  • Pimavanserin
  • Perflutren Lipid Microsphere
  • Pentamidine
  • Peginterferon Alfa-2b
  • Pazopanib
  • Pasireotide
  • Paritaprevir
  • Panobinostat
  • Paliperidone
  • Ondansetron
  • Ombitasvir
  • Ofloxacin
  • Octreotide
  • Nortriptyline
  • Norfloxacin
  • Nilotinib
  • Nafarelin
  • Moxifloxacin
  • Mifepristone
  • Metronidazole
  • Metolazone
  • Methadone
  • Mefloquine
  • Lumefantrine
  • Lorcainide
  • Lidoflazine
  • Lidocaine
  • Levofloxacin
  • Leuprolide
  • Lapatinib
  • Ketoconazole
  • Ivabradine
  • Isradipine
  • Isoflurane
  • Imipramine
  • Iloperidone
  • Ibutilide
  • Hydroxyzine
  • Hydroxychloroquine
  • Hydroquinidine
  • Hydroflumethiazide
  • Hydrochlorothiazide
  • Histrelin
  • Halothane
  • Haloperidol
  • Halofantrine
  • Granisetron
  • Goserelin
  • Gonadorelin
  • Gemifloxacin
  • Gatifloxacin
  • Foscarnet
  • Fluoxetine
  • Fluconazole
  • Flecainide
  • Fingolimod
  • Etravirine
  • Escitalopram
  • Erythromycin
  • Enflurane
  • Efavirenz
  • Duloxetine
  • Droperidol
  • Donepezil
  • Domperidone
  • Dolasetron
  • Dofetilide
  • Disopyramide
  • Dibenzepin
  • Deslorelin
  • Desipramine
  • Delavirdine
  • Delamanid
  • Degarelix
  • Dasatinib
  • Dasabuvir
  • Darifenacin
  • Dabrafenib
  • Cyclobenzaprine
  • Crizotinib
  • Cobicistat
  • Clozapine
  • Clomipramine
  • Clarithromycin
  • Citalopram
  • Ciprofloxacin
  • Chlorthalidone
  • Chlorpromazine
  • Chlorothiazide
  • Chloroquine
  • Chloral Hydrate
  • Buserelin
  • Bupropion
  • Bretylium
  • Boceprevir
  • Bendroflumethiazide
  • Bedaquiline
  • Azithromycin
  • Azimilide
  • Astemizole
  • Asenapine
  • Artemether
  • Arsenic Trioxide
  • Aripiprazole
  • Arbutamine
  • Aprindine
  • Apomorphine
  • Anagrelide
  • Amoxapine
  • Amitriptyline
  • Amiodarone
  • Alfuzosin
  • Ajmaline
  • Acecainide
  • Abiraterone

Taking flecainide with any of the subsequent medications could cause a heightened risk of some side effects; however, the combination of both medications could be the best way to treat your condition. If both medications are agreed upon between you and your physician, they will likely adjust the total dose for either or just one medication.

  • Verapamil
  • Propranolol
  • Paroxetine
  • Digoxin
  • Cimetidine

Other Interactions

Some medications should not be taken close to mealtime due to the potential of interactions taking place. The interaction listed below is potentially significant, but this list is not all-inclusive.

It is not suggested to combine flecainide with the following; however, certain instances may require the combination. If combined, your physician may adjust the dosage information or how frequently you take flecainide, or they may offer other suggestions regarding tobacco, alcohol, or food with this medication.

  • Milk

Patients with the following medical conditions should take caution with taking flecainide. This medication in combination with any of the following medical issues could cause side effects to increase, but the combination may not be preventable in certain circumstances. If flecainide is prescribed, your physician may be inclined to adjust the dose or frequency for how often this medication is taken, or they may give you other directions regarding the use of this medication.

Medical Interactions

Due to the potential of interaction, it is highly important that your physician is aware if you have other medical issues and are considering taking flecainide.

  • Shock triggered by a heart attack
  • Pacemaker patients (permanent). Take caution, this medication can cause issues between the pacemaker and the patient, causing additional follow-up physician monitoring
  • Low or high potassium within the blood (electrolyte imbalance). Correct this issue prior to taking flecainide
  • Liver disease
  • Kidney disease
  • Irregular heart rhythm (sick sinus syndrome). Take caution, conditions can be made worse
  • Heart rhythm issue (bundle branch block) no pacemaker
  • Heart disease (such as cardiomyopathy)
  • Heart attack (recent). Patients with these circumstances should avoid this medication
  • Congestive heart failure (severe)
  • Chronic atrial fibrillation
  • Abnormal heart rhythm (AV block) no pacemaker


Your physician must carefully check how you are reacting to flecainide regularly to ensure that the medication is working as it should. These checkups will give the doctor the opportunity to adjust the dosage information, if needed.

Death or cardiac arrest rates were increased when patients who had myocardial infarction and asymptomatic ventricular arrhythmias were given flecainide, rather than a placebo. Flecainide is a class IC agent and comes with potential risks. Carefully consider for any Class IC agent how evidence is missing for increased rates of living. This is typically unacceptable for patients who do not have ventricular arrhythmias that are not life threatening, even if there are signs that are not life-threatening but unpleasant taking place for the patient.

Patients who have chronic atrial fibrillation should not take flecainide. There have been case studies that examine how patients with ventricular proarrhythmic tendencies who were prescribed flecainide for atrial flutter/fibrillation experienced increased rates of death, ventricular fibrillation, ventricular tachycardia, and premature ventricular contractions.

Consult with your physician immediately if you experience any of subsequent side effects: breath shortness; weight gain; swelling of the feet, ankles, or hands; or chest pain. These could be signs of heart failure.

This medication can cause shifts in the heart rhythm. Conditions such as QT prolongation, QRS, or PR are conditions of atypical heart rhythm. These can trigger severe side effects such as fainting in patients. Consult with your physician immediately if symptoms become worse or do not become any better over time.

Your physician may encourage you to have a medical bracelet or a card for identification noting that you are taking flecainide.

Prior to having emergency care or surgery of any type (dental surgery is included), inform the medical team, dentist, or physician in charge that you are on flecainide.

This medication can trigger abnormal dizziness, lack of alertness, or lightheadedness for patients. Be sure that you are aware of your personal reactions to flecainide prior to driving, operating machinery, or performing any types of activities that could be perceived as dangerous if one is not alert or dizzy at all.

Patients who have been taking flecainide consistently for two weeks or more should not abruptly stop use. Consult with your physician for the most optimal method of reducing the total dose prior to ending dosage altogether.

Your physician should approve other medications prior to taking them. This refers to medications that are prescription, drugs that are not, and even vitamin or herbal remedies.

When choosing the right medication for you, it is important for patients to compare the potential dangers against the possible benefits that it may provide. You must make this choice with your physician. Consider the following aspects prior to taking flecainide.


Inform your physician if you currently have, or ever have had in the past, any type of allergic reaction that was unusual to any type of medication, or to flecainide. Also let your physician know if you have experienced other kinds of allergies, including to animals, preservatives, dyes, or foods. For products that are not prescribed through a pharmacist, always read and become familiar with the ingredients that are printed on the medication summary for any product you take.

Specific Demographic Use


Research to date has not discovered how flecainide and the side effects of the medication impact the pediatric population. Your physician may consider flecainide in circumstances where children have severe heart rhythm issues; however, effectiveness and safety has not yet been determined.


There is not current information on how elderly patients are affected by flecainide or the side effects of the medication. However, older patients tend to have more kidney problems related to age, which could cause a need for a different dose based on physician recommendation.


Either animal research has demonstrated a negative effect and not any suitable research has been conducted for women who are pregnant; or, there has not been any research completed in pregnant women or animals.


Research in women has demonstrated minimal risk for the baby when the mother takes flecainide while breastfeeding.


Flecainide must be stored far from extreme heat or freezing temperatures. It should be kept in a sealed medication container out of immediate sunlight. Moisture should be kept away from the container. Keep flecainide out of children's reach at all times. Never keep medications that are not needed any longer or that are out of date. Consult with your medical care professional to understand ways to dispose of unneeded medications.


Flecainide is an antiarrhythmic medication. It helps the heart tissue directly by reducing the speed of nerve impulses for the heart. This aids in maintaining normal rhythm of the heart overall, and treats arrhythmias such as paroxysmal atrial fibrillation/flutter and paroxysmal supraventricular tachycardia.

It is important to let your physician know if you are taking any other medications prior to taking flecainide. Additional medical issues and even allergies to medications can impact the effectiveness of this medication, be sure to inform your medical care professional of any conditions or allergies you may have. Patients will receive a unique prescription from their doctor based on their unique medical needs. Never change or alter your physician prior to having approval from your physician.