Tikosyn (Dofetilide) – Oral


Tikosyn may cause severe ventricular arrhythmias (a type of abnormal heart rhythm). If you start or restart Tikosyn, you may be admitted to a hospital for close monitoring for at least three days to minimize the risk of ventricular arrhythmia.

What Is Tikosyn?

Tikosyn (dofetilide) belongs to a class of medications called antiarrhythmic drugs. It treats severe, sometimes fatal, irregular heartbeat disorders of the atrium, the heart’s upper chamber. These disorders include atrial fibrillation or atrial flutter.

Tikosyn improves heart rhythm by relaxing an overactive heart to restore a steady heartbeat. It works by blocking the potassium channels to reduce specific electrical signals in the heart that can cause an irregular heartbeat. This decreases the risk of blood clots, heart attack, or stroke. It is also effective in maintaining sinus rhythm (normal heart rhythm) in people with atrial fibrillation.

Tikosyn may cause severe ventricular arrhythmias (abnormal heart rhythm involving the heart's bottom pumping chambers). You may need to be in a hospital for at least three days to be monitored closely when you start taking dofetilide. It is essential to follow your prescription to prevent treatment side effects.

This medicine is available only as prescription capsules to be taken by mouth.

Drug Facts

Generic Name: Dofetilide

Brand Name(s): Tikosyn

Drug Availability: Prescription

Administration Route: Oral

Therapeutic Classification: Antiarrhythmic

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Dofetilide

Dosage Form(s): Capsule

What Is Tikosyn Used For?

The Food and Drug Administration (FDA) approved Tikosyn to treat certain forms of atrial arrhythmias such as atrial fibrillation (a heart condition that causes an irregular and fast heart rate) or atrial flutter (a type of abnormal heart rate) and to maintain normal sinus rhythm (NSR) in adults.

To be specific, Tikosyn should only be used if atrial fibrillation or atrial flutter is causing severe symptoms, such as heart palpitations, chest pain, and shortness of breath. Tikosyn itself may cause changes in the heart rhythm and, in rare cases, can be fatal; therefore, it should be used under close monitoring of a healthcare provider during initial use.

How to Take Tikosyn

You'll spend a few days in the hospital when you first start taking Tikosyn. This is so a healthcare provider can closely monitor your heart rate and kidney function and determine your response to the medication. Your healthcare provider may change the dose based on your response during this time.

When taking Tikosyn at home, follow the directions on the prescription label carefully. If you do not understand how to take it, ask your healthcare provider or pharmacist to explain the instructions. Tikosyn is usually taken once or twice daily as prescribed, with or without food. Don't take more, less, or more often than prescribed. Do not abruptly stop taking your medication without asking your healthcare provider, even if you feel fine.


Store the capsules at room temperature (68–77 degrees Fahrenheit) away from light and moisture. Do not store it in the bathroom. Keep all medications locked away from the sight and reach of children and pets.

Do not keep unwanted or expired medication with you. Never discard unwanted medicines by flushing them down the toilet or pouring them into a drain unless instructed. Discard the treatment when expired or no longer needed through a drug take-back program. Contact your pharmacist or local law enforcement to discard your medication safely.

Off-Label Uses

Healthcare providers may prescribe dofetilde for off-label uses, meaning for conditions not specifically indicated by the FDA.

Tikosyn is sometimes used off-label for:

How Long Does Tikosyn Take to Work?

The time Tikosyn takes to work varies based on the individual. Mostly, it takes three days to show an improvement in the heart rhythm, while sometimes it may take longer to convert to a normal rhythm.

What Are the Side Effects of Tikosyn?

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at www.fda.gov/medwatch or 800-FDA-1088.

Common Side Effects

Tikosyn may cause some side effects, including:

  • Headache
  • Chest pain
  • Dizziness
  • Respiratory tract infection
  • Shortness of breath
  • Nausea
  • Flu-like symptoms
  • Difficulty falling asleep or staying asleep (insomnia)
  • Back pain
  • Diarrhea
  • Rash
  • Abdominal pain

Seek medical help if any of these symptoms become severe or do not go away.

Severe Side Effects

Some side effects can be severe and do not go away on their own. These include:

  • Ventricular arrhythmias, which can include symptoms like chest pain, dizziness or light-headedness, fainting, or shortness of breath
  • Heart block, with symptoms such as fainting, dizziness, chest pain, trouble breathing, nausea, and fatigue

Call your healthcare provider immediately or seek emergency treatment if you experience these symptoms.

Report Side Effects

Tikosyn may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Tikosyn Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (capsules):
    • For abnormal heart rhythm:
      • Adults—125 to 500 micrograms (mcg) two times a day. Your doctor may adjust your dose as needed.
      • Children—Use and dose must be determined by your doctor.


During your hospital stay, your healthcare provider may change your dose of Tikosyn based on your response to treatment. This may vary from person to person. People with kidney impairment will need a dosage adjustment based on calculated creatinine clearance.

Missed Dose

If you miss a dose of Tikosyn, take it as soon as you remember. If it is nearly the time for your next regular dose, skip the missed dose. Take your next dose at the scheduled time. Do not double the dose to make up for the missed one.

Overdose: What Happens If I Take Too Much Tikosyn?

Tikosyn overdoses were rare in clinical studies, with only two reported overdose cases in the clinical trial program.

An overdose of Tikosyn would likely result in excessive prolongation of the QT interval, known as long QT syndrome, which can cause a dangerous rapid heart rate and irregular ventricular rhythm.

Symptoms can include:

  • Heart palpitations
  • Seizure-like activity
  • Dizziness or fainting
  • Sudden cardiac arrest

In the case of an overdose, immediately call the Poison Control Center or a healthcare provider. If you take too much Tikosyn, you may need to be monitored in a medical setting for any adverse effects. Call 911 if you think you are experiencing life-threatening symptoms.

What Happens If I Overdose on Tikosyn?

If you think you or someone else may have overdosed on Tikosyn call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Tikosyn, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly and to check for unwanted effects. This will allow for changes to be made in the amount of medicine you are taking, if necessary.

Do not use this medicine together with cimetidine, dolutegravir, hydrochlorothiazide, hydrochlorothiazide/triamterene, ketoconazole, megestrol, prochlorperazine, trimethoprim, trimethoprim/sulfamethoxazole, or verapamil. Using these medicines together may cause serious unwanted effects.

Do not eat grapefruit or drink grapefruit juice while you are using this medicine. Grapefruit and grapefruit juice may change the amount of this medicine that is absorbed in the body.

Do not take other medicines unless they have been discussed with your doctor. This especially includes potassium supplements or salt substitutes containing potassium, or certain diuretics (eg, amiloride, spironolactone, triamterene).

What Are Reasons I Shouldn’t Take Tikosyn?

Tikosyn should not be used by certain people, such as those:

  • Who are allergic to dofetilide or any of the ingredients in dofetilide capsules
  • With a low potassium level in the blood, vomiting, diarrhea, sweating, loss of appetite, and decreased thirst
  • With heart or liver disease.
  • With long QT syndrome
  • Who have renal (kidney) diseases or are on kidney dialysis
  • Who are pregnant, plan to become pregnant, or are breastfeeding

Moreover, you should not take Tikosyn if you are using any of the following drugs:

Your healthcare provider will tell you not to take Tikosyn if you take these medications.

What Other Medications Interact With Tikosyn?

Dofetilide may interact with certain drugs. Consult your healthcare provider before taking Tikosyn if you take any of the following medicines:

  • Midamor (amiloride)
  • Antibiotics such as Ery-Tab (erythromycin), Biaxin XL (clarithromycin), gatifloxacin, and more
  • Antifungal drugs such as Diflucan (fluconazole), Nizoral (ketoconazole), and Sporanox (itraconazole)
  • Cannabinoids such as Marinol (dronabinol), Cesamet (nabilone), or marijuana (cannabis)
  • Lanoxin (digoxin)
  • Cardizem, Cartia XT, Taztia XT, and Tiazac (diltiazem)
  • Diuretics, also known as water pills, such as Lasix (furosemide)
  • Human immunodeficiency virus (HIV) protease inhibitors including Reyataz (atazanavir), Prezista (darunavir), and Norvir (ritonavir)
  • Asthma medications such as Accolate (zafirlukast)
  • Drugs for depression, mental health illness, or nausea
  • Other antiarrhythmic drugs such as Pacerone (amiodarone) and Fortamet, Glumetza, Glucophage, and Riomet (metformin)
  • Serzone (nefazodone)
  • Qualaquin (quinine)

Grapefruit juice can also interact with Tikosyn, potentially increasing dofetilide levels.

This may not be a complete list of medicines that interact with Tikosyn. Tell your prescribing healthcare provider or a pharmacist about all your prescriptions, over-the-counter (OTC)/nonprescription medications, vitamins, and herbal supplements.

What Medications Are Similar?

Tikosyn is characterized as a Class III antiarrhythmic. Other Class II antiarrhythmic drugs are:

  • Pacerone (amiodarone)
  • Bretylium (bretylium tosylate)
  • Multaq (dronedarone)
  • Corvert (ibutilide)
  • Betapace, Sorine, and Sotylize (sotalol)

Class III antiarrhythmics are drugs that block cardiac tissue potassium channels. However, some drugs in this class also affect sodium channels, calcium channels, and adrenergic receptors. The indications for these drugs vary but include atrial and ventricular arrhythmias.

These medications prolong the QT interval; therefore, torsades de pointes (a type of fast heart rhythm) is a potential complication of therapy.

Tikosyn effectively converts atrial dysrhythmias without causing heart failure and is used successfully in people with structural heart disease, including heart failure. It also doesn't cause many non-heart-related adverse reactions. Amiodarone, on the other hand, has the highest incidence of serious adverse effects and treatment withdrawals in clinical studies.

Unlike the other antiarrhythmics in its class, Tikosyn doesn't affect atrioventricular (AV) nodal conduction. The AV node is an important part of the heart's electrical system, as it controls the passage of the heart's electrical signal from the atria to the ventricles. Tikosyn can be used in symptomatic adults or those who can't take other antiarrhythmics.

Frequently Asked Questions

  • What is Tikosyn used for?

    Tikosyn contains dofetilide, an antiarrhythmic drug used to treat certain types of severe, perhaps fatal, irregular heartbeat such as atrial fibrillation. It restores normal heart rhythm and maintains a regular heartbeat.

  • How does Tikosyn work?

    Dofetilide, the drug in Tikosyn, works by blocking specific electrical signals in the heart that can cause an irregular heartbeat. It relaxes an overactive heart and helps improve the heart's pumping action, decreasing the risk of blood clots, heart attack, or stroke.

  • What drugs should not be taken with Tikosyn?

    The following drugs should not be used with Tikosyn:

  • How long does it take for Tikosyn to work?

    Tikosyn usually takes three days to improve your heart rhythm, but it may take longer in some cases. Your healthcare provider will keep monitoring your progress after each dose of Tikosyn. Once you have a normal heart rhythm, your provider will likely prescribe a maintenance dose.

  • What are the side effects of Tikosyn?

    Some common side effects of Tikosyn are:

    • Headache
    • Nausea
    • Flu-like symptoms
    • Back pain
    • Difficulty falling asleep or staying asleep

    Side effects that need medical attention and should not be ignored include:

    • Shortness of breath
    • Fast or irregular heartbeat
    • Pounding or slow heartbeat
    • Chest pain
    • Dizziness or light-headedness
    • Difficulty breathing
    • Severe diarrhea
  • How do I stop taking Tikosyn?

    Do not stop taking Tikosyn without the approval of your healthcare provider. Follow the healthcare provider's advice on diet, alcohol intake, and taking other drugs with Tikosyn.

How Can I Stay Healthy While Taking Tikosyn?

Dofetilide, the main ingredient in Tikosyn, is one of the most effective antiarrhythmic medications, with a nearly 60% likelihood of maintaining sinus rhythm.

Compared with other drugs in this class, Tikosyn can be safely used in people with significant cardiomyopathy and congestive heart failure. However, there is a risk of ventricular arrhythmias. When you start taking Tikosyn, you must be monitored in a healthcare setting.

While on Tikosyn, keep up with regular appointments and always follow the prescribing guidelines for the medication. Share a list of all your medications with your prescribing healthcare provider so they can warn you of any potential drug interactions. Seek medical help right away in the event of any new or worsening symptoms. 

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  3. Wolbrette DL, Hussain S, Maraj I, Naccarelli GV. A quarter of a century later: what is dofetilide's clinical role today? J Cardiovasc Pharmacol Ther. 2019;24(1):3-10. doi:10.1177/1074248418784288

  4. Johns Hopkins Medicine. Long QT syndrome.

  5. MedilinePlus. Dofetilide.

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  7. Sharma SP, Turagam M, Atkins D, et al. Safety of rapid switching from amiodarone to dofetilide in atrial fibrillation patients with an implantable cardioverter-defibrillator. Heart Rhythm. 2019;16(7):990-995. doi: 10.1016/j.hrthm.2019.01.028