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Generic name: mexiletine [ mex-IL-e-teen ]
Brand name: Mexitil
Dosage form: oral capsule (150 mg; 200 mg; 250 mg)
Drug class: Group I antiarrhythmics

Medically reviewed by on Oct 31, 2022. Written by Cerner Multum.

What is mexiletine?

Mexiletine affects the way that your heart beats.

Mexiletine is used to treat seriously irregular heartbeats.

Mexiletine may also be used for purposes not listed in this medication guide.


You should not use mexiletine if you have a serious heart condition such as "AV block" (unless you have a pacemaker).

Mexiletine may cause you to have abnormal liver function tests, especially if you also have congestive heart failure, or blood circulation problems.

Before taking this medicine

You should not use mexiletine if you are allergic to it, or if you have:

  • a serious heart condition such as "AV block" (unless you have a pacemaker).

To make sure mexiletine is safe for you, tell your doctor if you have:

  • liver disease;

  • congestive heart failure;

  • epilepsy or other seizure disorder;

  • a weak immune system (caused by disease or by using certain medicine); or

  • if you have recently taken other heart rhythm medicines (disopyramide, lidocaine, quinidine, or others).

FDA pregnancy category C. It is not known whether mexiletine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using mexiletine.

Mexiletine can pass into breast milk and may harm a nursing baby. You should not breast-feed while using this medicine.

How should I take mexiletine?

Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Mexiletine is usually given at first in a hospital.

Take mexiletine with food or an antacid to lessen stomach upset.

Your heart function may need to be checked using an electrocardiograph or ECG (sometimes called an EKG).

Do not skip doses, change your dosing schedule, or stop taking mexiletine without talking to your doctor. Changing your schedule could make your condition much worse.

Store at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Try not to miss any doses of this medication. Missing doses could be very dangerous.

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include nausea, drowsiness, confusion, feeling lightheaded, seizures, loss of consciousness, and a worsening irregular heartbeat.

What should I avoid while taking mexiletine?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Mexiletine side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Mexiletine may cause you to have abnormal liver function tests, especially if you also have congestive heart failure, or blood circulation problems.

Mexiletine may cause serious side effects. Call your doctor at once if you have:

  • chest pain;

  • a new or a worsening irregular heartbeat pattern; or

  • liver problems--nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects of mexiletine may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Mexiletine dosing information

Usual Adult Dose for Ventricular Tachycardia:

Initial dose: 200 mg orally every 8 hours when rapid control of arrhythmia is not essential.
A minimum of 2-3 days between dose adjustments is recommended.
Dose may be adjusted in 50 or 100 mg increments up or down.

Usual Pediatric Dose for Arrhythmias:

1.4 to 5 mg/kg/dose given every 8 hours. Begin with lower initial dosages and titrate to desired effects and serum concentrations.

What other drugs will affect mexiletine?

Other drugs may interact with mexiletine, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.