Uses
What is mexiletine used for?
Mexiletine is commonly used to treat an abnormal heartbeat or rhythm in the lower parts of the heart, called the ventricles. This is called ventricular arrhythmia. Mexiletine is only for people with serious ventricular arrhythmias.
Mexiletine may also be used for other conditions as determined by your healthcare provider.
How does mexiletine work (mechanism of action)?
Mexiletine works in the heart by blocking certain nerve signals. This slows down the abnormal heart rhythm in the ventricles to allow for a normal heart rhythm.
How is mexiletine supplied (dosage forms)?
Mexiletine is available in the following dosage forms that are taken by mouth.
- 150 mg oral capsules
- 200 mg oral capsules
- 250 mg oral capsules
How should I store mexiletine?
Mexiletine should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C), for shorter periods of time, such as when transporting it. Store in a cool, dry place, in a tightly closed container.
Side Effects
What are the most common side effects of mexiletine?
The most common side effects of mexiletine are listed below. Tell your healthcare provider if you have any of these side effects that bother you.
- Nausea and vomiting
- Heartburn
- Dizziness or lightheadedness
- Shaking (tremors)
- Nervousness
- Trouble with coordination
There may be other side effects of mexiletine 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 www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of mexiletine?
While less common, the most serious side effects of mexiletine are described below, along with what to do if they happen.
Severe Allergic Reactions. Mexiletine can cause a specific type of allergic reaction called DRESS. DRESS stands for Drug Reaction with Eosinophilia and Systemic Symptoms. It is also sometimes called multi-organ hypersensitivity. This is a reaction that can affect multiple parts of the body including your liver, kidneys, and heart. Stop using mexiletine and get help right away if you have any of the following symptoms of this serious allergic reaction.
- Skin rash or pale red bumps on the skin called hives
- Fever or general ill feeling
- Swollen lymph nodes
- Shortness of breath
- Swelling in your feet, ankles, or legs
- Dark colored urine
- Your skin or the whites of your eyes turning yellowish in color (also called jaundice)
Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking mexiletine. Call your healthcare provider right away if you have any of the following symptoms of liver damage.
- Nausea or vomiting
- Stomach or belly pain
- Fever
- Weakness or unusual tiredness
- Itching
- Loss of appetite
- Light-colored poop
- Dark-colored urine
- Your skin or the whites of your eyes turning yellowish in color (also called jaundice)
Blood Disorders. Mexiletine may lower both white blood cells, (which help fight infections in your body), and platelets (which help form blood clots to prevent bleeding). Call your healthcare provider right away if you have any of the following symptoms of these blood disorders.
- Fever
- Easy bruising or bleeding
- Pink, red, or brown urine (pee)
- Red or black stools (looks like tar)
- Unusual weakness or tiredness
- Frequent infection
Warnings & Precautions
Who should not use mexiletine?
Allergies to Ingredients. People who are allergic to any of the following should not take mexiletine.
- Mexiletine
- Any of the ingredients in the specific product dispensed
Your pharmacist can tell you all of the ingredients in the specific mexiletine products they stock.
Heart Block. People who have heart block, also called atrioventricular (AV) block, should not use mexiletine unless they have a pacemaker and are continuously monitored.
What should I know about mexiletine before using it?
Do not take mexiletine unless it has been prescribed to you by a healthcare provider. Take it as prescribed.
Do not share mexiletine with other people, even if they have the same condition as you. It may harm them.
Keep mexiletine out of the reach of children.
Mexiletine can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how mexiletine affects you.
Take mexiletine with food or antacids.
What should I tell my healthcare provider before using mexiletine?
Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if mexiletine is right for you.
In particular, make sure that you discuss any of the following.
Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.
- Heart block, including atrioventricular block (AV block), with or without a pacemaker
- Abnormal heart conduction, such as sinus node dysfunction
- Heart disease
- History of a heart attack
- Low blood pressure, also called hypotension
- Liver disease
- Blood disorders, such as low white blood cells (leukopenia), or low platelets (thrombocytopenia)
- Seizure disorder
Heart Failure. Tell your healthcare provider if you have heart failure. Mexiletine may worsen the symptoms of heart failure.
Other Medicines and Supplements. Mexiletine may interact with other medicines and supplements. Before using mexiletine, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section below for more details.
Pregnancy. It is not known if or how mexiletine could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take mexiletine while you are pregnant or trying to get pregnant.
Breastfeeding. Mexiletine passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take mexiletine while breastfeeding.
Interactions
Does mexiletine interact with foods or drinks?
There are no known interactions between mexiletine and foods or drinks.
It is unknown if drinking alcohol will affect mexiletine, but both mexiletine and alcohol can increase your risk of bleeding. In addition, the risk of lightheadedness and dizziness may be increased if you drink alcohol while taking mexiletine. It is best to limit the amount of alcohol you drink.
Does mexiletine interact with other medicines (drug interactions)?
Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.
In particular, make sure that you discuss if you are using any of the following before using mexiletine.
- Fluvoxamine, which is a medicine commonly used for depression
- Propafenone, which is a medicine used for abnormal heartbeat or rhythm (arrhythmia)
- Rifampin, which is a medicine commonly used for infections
- Cimetidine, which is a medicine commonly used for heartburn
- Products that contain caffeine, which is often found in medicines for reducing water weight (diuretics), staying awake, headaches, and hangover relief
- Theophylline, which is a medicine commonly used to treat lung disease
- Phenytoin (Dilantin, Phenytek, and others) or phenobarbital, which are medicines commonly used to treat seizures
Some other medicines may alter the blood levels of mexiletine, and vice versa. Tell your healthcare provider about all medicines that you take or have recently taken.
Overdose/Missed Dose
What should I do if I accidentally use too much mexiletine?
If you or someone else has used too much mexiletine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.
What should I do if I miss a dose of mexiletine?
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.
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