Before taking mexiletine,
tell your doctor and pharmacist if you are allergic to mexiletine, lidocaine, any other medications, or any of the ingredients in mexiletine. Ask your pharmacist for a list of the ingredients.
tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: acetazolamide (Diamox); aluminum-magnesium hydroxide (Gaviscon, Maalox, Mylanta, others); amiodarone (Cordarone, Pacerone); atropine (in Lomotil, in Lonox, in Motofen); bupropion (Wellbutrin, Zyban); caffeine-containing medications (Cafergot, Esgic, Esgic Plus, Fioricet, NoDoz, Norgesic, others); chlorpheniramine (Chlor-Trimeton); cimetidine (Tagamet); clomipramine (Anafranil); diuretics ('water pills'); fluoroquinolones such as ciprofloxacin (Cipro), levofloxacin (Levaquin), moxifloxacin (Avelox), norfloxacin (Noroxin), and ofloxacin (Floxin); haloperidol (Haldol); methenamine (Hiprex, Urex); metoclopramide (Reglan); narcotic medications for pain; phenobarbital; phenytoin (Dilantin, Phenytek); potassium citrate (Urocit-K); propafenone (Rythmol); rifampin (Rifadin, Rimactane); ritonavir (Norvir, in Kaletra); certain selective serotonin reuptake inhibitors (SSRIs) such as duloxetine (Cymbalta), fluoxetine (Prozac, Sarafem), fluvoxamine, and paroxetine (Paxil); sodium bicarbonate (Soda Mint, baking soda); theophylline (Theolair, Theochron, Uniphyl); and ticlopidine (Ticlid). Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Many other medications may also interact with mexiletine, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
tell your doctor if you have or have ever had a heart attack, heart failure, low blood pressure, liver disease, or seizures.
tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking mexiletine, call your doctor.
if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking mexiletine.
you should know that mexiletine may make you dizzy or lightheaded. Do not drive a car or operate machinery until you know how this medication affects you.
tell your doctor if you use tobacco products. Cigarette smoking may decrease the effectiveness of this medication.