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Mexitil Side Effects

Generic name: mexiletine

Medically reviewed by Last updated on Mar 26, 2022.

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

For the Consumer

Applies to mexiletine: oral capsule


Oral route (Capsule)

Considering the known proarrhythmic properties of mexiletine and the lack of evidence of improved survival for any antiarrhythmic drug in patients without life-threatening arrhythmias, the use of mexiletine as well as other antiarrhythmic agents should be reserved for patients with life-threatening ventricular arrhythmia.

Side effects requiring immediate medical attention

Along with its needed effects, mexiletine (the active ingredient contained in Mexitil) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur while taking mexiletine:

Less common


  • Convulsions (seizures)
  • fever or chills
  • unusual bleeding or bruising

Side effects not requiring immediate medical attention

Some side effects of mexiletine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

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"

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

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

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

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

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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

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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

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.