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.

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.

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.

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.

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.

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.

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Talk to your doctor about drinking caffeine-containing beverages while taking this medicine.

Tell your doctor if you are a vegetarian or if you usually eat large amounts of citrus fruits, cranberries, vegetables, meat, or dairy products. If you do not regularly eat large amounts of these foods, continue your normal diet.

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

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:

• heartburn, upset stomach, nausea, vomiting;

• dizziness, feeling lightheaded;

• tremors, feeling nervous;

• problems with coordination; or

• blurred vision.

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.

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.

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your body's response to mexiletine.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.