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To decrease the chance of your getting a different type of dangerous abnormal heartbeat, Dofetilide treatment must be started or re-started while you are in the hospital. Feeling faint, dizziness/lightheadedness, or having fast heartbeats are symptoms of this abnormal heartbeat. Call your doctor or the emergency room as soon as possible if you have any of these symptoms. While in the hospital, your kidney function and heart rhythm will be monitored for a minimum of 3 days. This helps the doctor choose the right Dofetilide dose for you.

What are Dofetilide Capsules?

Dofetilide Capsules are a prescription medicine for highly symptomatic atrial fibrillation or atrial flutter (irregular heartbeats). Dofetilide Capsules may help by converting irregular heartbeats to normal rhythm. It may also help by keeping the normal rhythm for a longer period of time. It has not been shown to work on certain types of irregular heartbeats that may come and go on their own.

Who should not take Dofetilide Capsules?

Do not take Dofetilide Capsules if you:

  • have congenital or acquired long QT syndrome; a disorder of the heartbeat which may be present from birth, or it may be acquired as a result of certain medical conditions or from taking certain medications. People with long QT syndrome may have symptoms including unusually rapid heartbeat, fainting, and seizures. Sudden cardiac death may also result from long QT syndrome.
  • if you have serious kidney problems or are on kidney dialysis; are taking certain other medications, including cimetidine, verapamil, ketoconazole, trimethoprim alone or in combination with sulfamethoxazole, prochlorperazine, megestrol, dolutegravir, or hydrochlorothiazide alone or in combination with other medicines such as triamterene; or are allergic to dofetilide or other ingredients in Dofetilide Capsules.

What are the possible side effects of Dofetilide Capsules?

The most common side effects of Dofetilide Capsules are headache, chest pain, and dizziness. Dofetilide Capsules may also cause other side effects. If you are concerned about these or any other side effects, ask your doctor.

Call your doctor right away if you have signs of electrolyte imbalance:

  • severe diarrhea
  • unusual sweating
  • vomiting
  • not hungry (loss of appetite)
  • increased thirst (drinking more than normal)

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit or call 1-800-FDA-1088. You may also report negative side effects of Mayne Pharma Dofetilide Capsules to 1-844-825-8500.


The risk information provided here is not comprehensive. To learn more about Dofetilide Capsules, talk with your doctor. The FDA-approved labeling can be found at FULL PRESCRIBING INFO