What are the most common side effects of dofetilide?

The most common side effects of dofetilide are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

Headache

Chest pain

Dizziness

There may be other side effects of dofetilide that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at  or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at  or by calling 866-234-2345.

While less common, the most serious side effects of dofetilide are described below, along with what to do if they happen.

Severe Allergic Reactions. Dofetilide may cause allergic reactions, which can be serious. Stop taking dofetilide and get help right away if you have any of the following symptoms of a serious allergic reaction.

Heart Rhythm Changes. Dofetilide may cause heart rhythm problems, including Torsade de Pointes, which can be fatal. Some people have a higher risk of this, including people with existing heart disease or who take other medicines that affect the heart. Get emergency help if you have any of the following signs of heart rhythm changes.

Chest pain

Shortness of breath

Feeling dizzy, lightheaded, or fainting

Changes in your heart rate or rhythm, such as a fast, slow, pounding or skipping heartbeat

Electrolyte Changes. Dofetilide may cause changes to the levels of certain minerals in your body, called electrolytes. For example, it may cause low potassium levels (hypokalemia), low sodium levels (hyponatremia), or low chloride levels (hypochloremia). These changes can be serious. Keep appointments for blood work, so that your healthcare provider can check your electrolyte levels, especially if you take certain other medicines. Call your healthcare provider if you have any of the following symptoms of electrolyte changes.