SIDE EFFECTS: See also Warning section.
Nausea, vomiting, heartburn, dizziness, lightheadedness, shakiness of hands/arms, nervousness, and problems with muscle control (coordination difficulties) may occur. Less common side effects may include sleep problems, weakness, tiredness, blurred vision, dry mouth, headache, diarrhea, constipation, and mild speaking difficulties. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Tell your doctor immediately if any of these unlikely but serious side effects occur: shortness of breath, unusual sweating, mental/mood changes (e.g., confusion, hallucinations, depression, memory loss), tingling/numbness, ringing in the ears, loss of appetite, swelling, sore throat, decreased sexual interest/ability, problems starting the flow of urine.
Tell your doctor immediately if any of these rare but very serious side effects occur: fainting, worsening symptoms of heart failure (e.g., ankle/leg swelling, increased tiredness, increased shortness of breath when lying down), very slow heartbeat, signs of liver problems (e.g., persistent nausea/vomiting, stomach/abdominal pain, yellowing eyes/skin, dark urine, severe tiredness), butterfly-shaped facial rash with unusual tiredness, joint/muscle aches, easy bleeding/bruising, signs of serious infection (e.g., fever, severe chills, persistent sore throat).
Seek immediate medical attention if any of these rare but very serious side effects occur: seizures, chest pain.
A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching, swelling, severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
Contact your doctor for medical advice about side effects. The following numbers do not provide medical advice, but in the US you may report side effects to the Food and Drug Administration (FDA) at 1-800-FDA-1088. In Canada, you may call Health Canada at 1-866-234-2345.
PRECAUTIONS: See also Warning section.
Before taking mexiletine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies.
This medication should generally not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: certain heart rhythm problems (second- or third-degree atrioventricular block unless you have a pacemaker), shock due to the heart not pumping well (e.g., very low blood pressure and loss of consciousness).
Before using this medication, tell your doctor or pharmacist your medical history, especially of: low blood pressure, heart failure with severe symptoms (e.g., swelling of feet/legs, severe tiredness, shortness of breath), liver problems, recent heart attack (within the past 2 years), seizures, abnormal blood minerals (high or low potassium), conditions that may make the urine more alkaline (e.g., strict vegetarian diet, renal tubular acidosis).
Contact your doctor immediately if you develop other illnesses/conditions such as prolonged or large quantities of diarrhea, excessive sweating, vomiting, prolonged loss of appetite or desire to drink water. These conditions could cause you to have serious changes in blood minerals leading to increased side effects from mexiletine.
This drug may make you dizzy or cause blurred vision. Use caution while driving, using machinery, or doing any activity that requires alertness or clear vision. Avoid alcoholic beverages.
During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.
This medication passes into breast milk and may have undesirable effects on a nursing infant. Consult your doctor before breast-feeding.