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Dofetilide (By mouth)

Dofetilide (doe-FET-i-lide)

Treats an uneven heartbeat.

Brand Name(s):


There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. Do not use it if you had an allergic reaction to dofetilide, if you have long QT syndrome or severe kidney disease, or if you are on a dialysis.

How to Use This Medicine:


  • Your doctor will start you on this medicine while you are in the hospital so your heart rhythm can be monitored. You will need to stay in the hospital for at least 3 days so the doctor can check your progress.
  • Once you are released from the hospital, take your medicine as directed.
  • This medicine should come with a Medication Guide. Ask your pharmacist for a copy if you do not have one.
  • Missed dose: If you miss a dose of this medicine, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Do not use this medicine together with cimetidine, dolutegravir, hydrochlorothiazide, hydrochlorothiazide/triamterene, ketoconazole, megestrol, prochlorperazine, trimethoprim, trimethoprim/sulfamethoxazole, or verapamil.
  • Some foods and medicines can affect how dofetilide works. Tell your doctor if you are using diltiazem, metformin, quinine, or zafirlukast.
  • Tell your doctor if you are also using certain diuretics (such as amiloride, spironolactone, triamterene), blood pressure medicines, medicine for depression, a phenothiazine medicine, medicine for infections, or medicine for HIV/AIDS.
  • Do not eat grapefruit or drink grapefruit juice while you are using this medicine.

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, heart disease, other heart rhythm problems, or mineral imbalance (such as low levels of magnesium or potassium in the blood).
  • This medicine may cause the following problems:
    • Ventricular arrhythmia
    • QT prolongation
  • Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Chest pain or trouble breathing
  • Fainting, dizziness, or lightheadedness
  • Fast, slow, or pounding heartbeat
  • Severe diarrhea, vomiting, loss of appetite, increased thirst, sweating, muscle cramps

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 5/1/2020

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