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Important Note

The following information is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist or other healthcare professional. It should not be construed to indicate that use of the drug is safe, appropriate, or effective for you. Consult your healthcare professional before using this drug.




WARNING: This medication sometimes produces new irregular heartbeats (arrhythmias). Therefore, it should be used in carefully selected patients. Consult your doctor or pharmacist for more information.


This medication is used to treat irregular heart rhythms (arrhythmias) and maintain a normal heart rate.

How To Use

This medication should be taken with food, milk or an antacid to prevent stomach upset. Take this medication with a full glass (8 oz or 240 ml) of water unless your doctor directs you otherwise. Do not lie down for 30 minutes after taking this medication. This medication works best when there is a constant level of the drug in your body. To do this, take each dose exactly as prescribed at evenly spaced intervals throughout the day and night. Try to take each dose at the same time each day. Do not stop taking this medication without consulting your doctor. Some conditions may become worse when the drug is suddenly stopped.

Side Effects

Nausea, vomiting, heartburn, dizziness, tremor, changes in vision, nervousness, confusion, headache, fatigue, depression, changes in sleep habits, numbness or tingling especially of the hands or feet, ringing in the ears may occur. If any of these symptoms persist or worsen, notify your doctor. Inform your doctor if you develop: chest pain, rapid heartbeat, general weakness, yellowing of the eyes or skin, fever or sore throat. In the unlikely event you have an allergic reaction to this drug, seek immediate medical attention. Symptoms of an allergic reaction include: rash, itching, swelling, dizziness, breathing trouble. If you notice other effects not listed above, contact your doctor or pharmacist.


Tell your doctor your medical history, especially: congestive heart failure, low blood pressure, liver disease, history of seizures, any allergies- especially allergies to amide- type anesthetics (e.g., lidocaine, tocainamide) or other drugs. Mexiletine should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor. Mexiletine is excreted into breast milk. Because the possibility of harm to nursing infants exists, consult your doctor before breast-feeding.

Drug Interactions

Tell your doctor of all medications you may use (both prescription and nonprescription), especially: rifampin, theophylline, caffeine, phenytoin, metoclopramide, sodium bicarbonate, potassium citrate, ammonium chloride. Smoking can decrease the effects of this drug. Do not start or stop any medicine without doctor or pharmacist approval.


If overdose is suspected, contact your local poison control center or emergency room immediately. Symptoms of overdose may include dizziness, drowsiness, nausea, low blood pressure, slow pulse, tingling in fingers or toes, seizures, and loss of consciousness.


Your doctor may want you to check your pulse rate every day while you take this medication. Learn how to monitor your pulse.

Missed Dose

Take any missed dose as soon as possible but not if it is almost time for the next dose. If it is time for the next dose, skip the missed dose and resume your regular schedule. Do not double the dose to catch up.


Store at room temperature and keep away from moisture and sunlight. Do not store in the bathroom.

Medical Alert

Your condition can cause complications in a medical emergency. For enrollment information call MedicAlert at 1-800-854-1166 (USA), or 1-800-668-1507 (Canada).