Mexiletine treats serious arrhythmias (irregular heartbeats). Take with food or an antacid to prevent stomach upset.

Mexiletine Overview

Reviewed: September 12, 2013

Mexiletine is a prescription medication used to treat certain types of life-threatening, ventricular arrhythmias (irregular heartbeats). This medication belongs to a group of drugs called Class IB antiarrhythmics which work by blocking sodium channels in the heart, slowing down electrical signals to stabilize heart rhythm.

Mexiletine comes in capsule form. It is usually taken 3 times daily, every 8 hours. Sometimes it must be taken twice daily, every 12 hours. Take mexiletine with food or an antacid to prevent stomach upset. 

Common side effects include poor upset stomach, lightheadedness, and dizziness. Do not drive or operate heavy machinery until you know how it affects you.


How was your experience with Mexiletine?

First, a little about yourself

Tell us about yourself in a few words?

What tips would you provide a friend before taking Mexiletine?

What are you taking Mexiletine for?

Choose one
  • Other
  • Arrhythmias, Cardiac
  • Diabetic Neuropathies
  • Ventricular Fibrillation
  • Ventricular Premature Complexes

How long have you been taking it?

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  • Less than a week
  • A couple weeks
  • A month or so
  • A few months
  • A year or so
  • Two years or more

How well did Mexiletine work for you?

Did you experience many side effects while taking this drug?

How likely would you be to recommend Mexiletine to a friend?

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Uses of Mexiletine

Mexiletine is a prescription medication used to treat life-threatening, ventricular arrhythmias (irregular heartbeats).

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Mexiletine Brand Names

Mexiletine may be found in some form under the following brand names:

Mexiletine Drug Class

Mexiletine is part of the drug class:

Side Effects of Mexiletine

Common side effects include:

  • nausea
  • vomiting
  • heartburn
  • changes in appetite
  • lightheadedness or dizziness
  • shaking of a part of your body that you cannot control
  • loss of coordination
  • numbness or tingling sensation
  • headache
  • blurred vision
  • nervousness
  • difficulty speaking
  • swelling of the hands, feet, ankles, or lower legs
  • rash

This is not a complete list of mexiletine side effects. Ask your doctor or pharmacist for more information.

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


Mexiletine FDA Warning


Mortality: In the National Heart, Lung and Blood Institute's Cardiac Arrhythmia Suppression Trial (CAST), a long-term, multicentered, randomized, double-blind study in patients with asymptomatic non-life-threatening ventricular arrhythmias who had a myocardial infarction more than six days but less than two years previously, an excessive mortality or non-fatal cardiac arrest rate (7.7%) was seen in patients treated with encainide or flecainide compared with that seen in patients assigned to carefully matched placebo-treated groups (3.0%). The average duration of treatment with encainide or flecainide in this study was ten months.

The applicability of the CAST results to other populations (e.g., those without recent myocardial infarction) is uncertain. Considering the known proarrhythmic properties of mexiletine and the lack of evidence of improved survival for any antiarrhythmic drug in patients without life-threatening arrhythmias, the use of mexiletine as well as other antiarrhythmic agents should be reserved for patients with life-threatening ventricular arrhythmia.