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Mexitil Side Effects

Generic Name: mexiletine

Note: This page contains information about the side effects of mexiletine. Some of the dosage forms included on this document may not apply to the brand name Mexitil.

For the Consumer

Applies to mexiletine: oral capsule, oral capsule extended release

In addition to its needed effects, some unwanted effects may be caused by mexiletine (the active ingredient contained in Mexitil). In the event that any of these side effects do occur, they may require medical attention.

Severity: Moderate

If any of the following side effects occur while taking mexiletine, check with your doctor or nurse as soon as possible:

Less common:
  • Chest pain
  • fast or irregular heartbeat
  • shortness of breath
  • Convulsions (seizures)
  • fever or chills
  • unusual bleeding or bruising

Minor Side Effects

Some of the side effects that can occur with mexiletine may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common:
  • Dizziness or lightheadedness
  • heartburn
  • nausea and vomiting
  • nervousness
  • trembling or shaking of the hands
  • unsteadiness or difficulty in walking
Less common:
  • Blurred vision
  • confusion
  • constipation or diarrhea
  • headache
  • numbness or tingling of fingers and toes
  • ringing in the ears
  • skin rash
  • slurred speech
  • trouble in sleeping
  • unusual tiredness or weakness

For Healthcare Professionals

Applies to mexiletine: oral capsule


Generally, mexiletine (the active ingredient contained in Mexitil) has been well tolerated. Side effects usually have been reversible and dose-related. The most common side effects associated with mexiletine therapy have been gastrointestinal and nervous system effects. The incidence of side effects increases at serum levels greater than 2.0 mcg/mL.[Ref]


A case of mexiletine (the active ingredient contained in Mexitil) esophageal ulceration has been reported. Mexiletine was continued following a dosage reduction and an increase in the dosing interval.[Ref]

Gastrointestinal side effects have occurred most frequently. Nausea, anorexia, constipation and dyspepsia have been reported in 10% to 40% of patients, primarily during the first 3 to 4 weeks of therapy. Administration with food usually reduced gastrointestinal side effects. Diarrhea was reported in 7% of patients. Dysphagia, salivary changes, altered taste, changes in oral mucosa, hiccups, peptic ulcer disease, upper GI bleeding, and esophageal ulceration have been reported rarely.[Ref]

Nervous system

Nervous system side effects have included fine hand tremor (10%), dizziness (up to 25%), and difficulties with coordination (10.2%). These symptoms may be the first signs of toxicity. Ataxia, dysarthria, drowsiness, paresthesias, nervousness, speech difficulties, depression, and confusion have been reported less frequently. Short-term memory loss, malaise, seizures, and loss of consciousness have occurred.[Ref]


Cardiovascular symptoms of palpitation and chest pain have occurred in up to 7.5% of patients. A proarrhythmic effect has been reported in approximately 10% of patients and angina 1.7%. Mexiletine (the active ingredient contained in Mexitil) has little effect on cardiac contractility. Syncope, hypotension, hypertension, bradycardia, conduction disturbances, atrial arrhythmias, edema, and congestive heart failure have occurred.[Ref]

Rare cases of torsades de pointes have been associated with mexiletine. New or worsened congestive heart failure has been reported in 1% to 3% of patients.

A case of new first-degree AV heart block and left bundle branch block associated with elevated mexiletine serum levels (34 mcg/mL) was reported.[Ref]


Hematologic side effects are rare and have included reports of thrombocytopenia, which is thought to be due to an IgM cold agglutinin.[Ref]


A generalized pruritic, erythematous, papular rash has been reported in a 77-year-old man.[Ref]

Hypersensitivity rashes have been reported rarely.[Ref]


Hepatic side effects have been rare. Isolated cases of mild reversible elevations in liver function tests which resolved after two to three weeks after stopping mexiletine (the active ingredient contained in Mexitil) have occurred. Rare cases of severe hepatitis or acute hepatic necrosis have been reported.[Ref]


Respiratory abnormalities including dyspnea have occurred in 3.7% to 5.7% of patients.[Ref]

A case of fatal diffuse interstitial pulmonary fibrosis has been associated with mexiletine in a 75-year-old man who had previously taken procainamide and disopyramide. Symptoms of dyspnea preceded chest X-ray abnormalities by months. The diagnosis was made following pulmonary function tests, chest CT scan, and an open lung biopsy.[Ref]


Ocular side effects including diplopia, nystagmus, and blurred vision have been reported in up to 7.5% of patients.[Ref]


Dermatologic side effects have been uncommon, however, rash has been reported in up to 4.2% of patients. Rare cases of exfoliative dermatitis and Stevens-Johnson Syndrome have occurred. Diaphoresis, hot flashes, and dry skin have been reported.[Ref]


Genitourinary side effects including urinary hesitancy and retention have occurred rarely. Impotence and decreased libido have been reported.[Ref]


Psychiatric side effects including psychosis and hallucinations have been reported.[Ref]


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2. "Multum Information Services, Inc. Expert Review Panel"

3. Podrid PJ, Lown B "Mexiletine for ventricular arrhythmias." Am J Cardiol 47 (1981): 895-902

4. Murray KT, Barbey JT, Kopelman HA, et al "Mexiletine and tocainide: a comparison of antiarrhythmic efficacy, adverse effects, and predictive value of lidocaine testing." Clin Pharmacol Ther 45 (1989): 553-61

5. Adler JB, Goldberg RI "Mexiletine-induced pill esophagitis." Am J Gastroenterol 85 (1990): 629-30

6. Haggman DL, Maloney JD, Morant VA, et al "Mexiletine therapy in patients with chronic drug-resistant malignant ventricular arrhythmias." Cleve Clin Q 53 (1986): 171-9

7. Kerin NZ, Aragon E, Marinescu G, et al "Mexiletine: long-term efficacy and side effects in patients with chronic drug-resistant potentially lethal ventricular arrhythmias." Arch Intern Med 150 (1990): 381-4

8. Wulf BG "Mexiletine and tocainide: orally active congeners of lidocaine." Clin Pharm 2 (1983): 340-6

9. Fenster PE, Comess KA "Pharmacology and clinical use of mexiletine." Pharmacotherapy 6 (1986): 1-9

10. Monk JP, Brogden RN "Mexiletine: a review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in the treatment of arrhythmias." Drugs 40 (1990): 374-411

11. Manolis AS, Deering TF, Cameron J, Estes NA, 3d "Mexiletine: pharmacology and therapeutic use." Clin Cardiol 13 (1990): 349-59

12. Poole JE, Werner JA, Bardy GH, et al "Intolerance and ineffectiveness of mexiletine in patients with serious ventricular arrhythmias." Am Heart J 112 (1986): 322-6

13. Campbell RW "Mexiletine." N Engl J Med 316 (1987): 29-34

14. Johansson BW, Stavenow L, Hanson A "Long-term clinical experience with mexiletine." Am Heart J 107 (1984): 1099-102

15. Stavenow L, Hanson A, Johansson BW "Mexiletine in treatment of ventricular arrhythmias." Acta Med Scand 205 (1979): 411-5

16. Chew CY, Collett J, Singh BN "Mexiletine: a review of its pharmacological properties and therapeutic efficacy in arrhythmias." Drugs 17 (1979): 161-81

17. Mehta J, Conti CR "Mexiletine, a new antiarrhythmic agent, for treatment of premature ventricular complexes." Am J Cardiol 49 (1982): 455-60

18. Cocco G, Strozzi C, Chu D, Pansini R "Torsades de pointes as a manifestation of mexiletine toxicity." Am Heart J 100 (1980): 878-80

19. Nora MO, Chandrasekaran K, Hammill SC, Reeder GS "Prolongation of ventricular depolarization: ECG manifestation of mexiletine toxicity." Chest 95 (1989): 925-8

20. Ravid S, Podrid PJ, Lampert S, Lown B "Congestive heart failure induced by six of the newer antiarrhythmic drugs." J Am Coll Cardiol 14 (1989): 1326-30

21. Fasola GP, D'Osualdo F, de Pangher V, Barducci E "Thrombocytopenia and mexiletine." Ann Intern Med 100 (1984): 162

22. Girmann G, Pees H, Scheurlen PG "Pseudothrombocytopenia and mexiletine." Ann Intern Med 100 (1984): 767

23. Kikuchi K, Tsunoda T, Tagami H "Generalized drug eruption due to mexiletine hydrochloride: topical provocation on previously involved skin." Contact Dermatitis 25 (1991): 70-1

24. Bero CJ, Rihn TL "Possible association of pulmonary fibrosis with mexiletine." DICP 25 (1991): 1329-31

Not all side effects for Mexitil may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.