Mexiletine: Side Effects, Uses & Monitoring
Mexiletine hydrochloride capsules USP are indicated for the treatment of documented ventricular arrhythmias, such as sustained ventricular tachycardia, that, in the judgment of the physician, are life-threatening.
- Data source
- FDA labeling via NIH DailyMed (label c528aae3…)
- Label version
- current
- Last reviewed
- 2026
Reported adverse reactions
Reactions listed in current FDA labeling, with the highest frequency reported across summarized placebo-controlled trials.
| Adverse reaction (as reported in labeling) | Reported frequency* |
|---|---|
| Nausea/vomiting/heartburn | 39.6% |
| Nausea/vomiting/ heartburn | 39.3% |
| Diarrhea | 33.2% |
| Dizziness/lightheadedness | 26.4% |
| Changes in sleep habits | 16.3% |
| Dry mouth | 14.5% |
| Tremor | 13.2% |
| Constipation | 11.6% |
| Nervousness | 11.3% |
| Palpitations | 10.2% |
| Dyspnea/respiratory | 10.2% |
| Coordination difficulties | 9.4% |
| Chest pain | 7.5% |
| Headache | 7.5% |
| Blurred vision/visual disturbances | 7.5% |
| Arthralgia | 5.1% |
| Weakness | 4.1% |
| Tinnitus | 4.1% |
| Paresthesias/numbness | 3.8% |
| Rash | 3.8% |
*Highest percentage reported for the active moiety across placebo-controlled trial tables in current FDA labeling. Values reflect trial reporting, not your individual risk.
Labeled uses (from FDA prescribing information)
Mexiletine hydrochloride capsules USP are indicated for the treatment of documented ventricular arrhythmias, such as sustained ventricular tachycardia, that, in the judgment of the physician, are life-threatening. Because of the proarrhythmic effects of mexiletine, its use with lesser arrhythmias is generally not recommended. Treatment of patients with asymptomatic ventricular premature contractions should be avoided. Initiation of mexiletine treatment, as with other antiarrhythmic agents used to treat life-threatening arrhythmias, should be carried out in the hospital. Antiarrhythmic drugs have not been shown to enhance survival in patients with ventricular arrhythmias.
Frequently Asked Questions
What is Mexiletine used for?
FDA labeling lists the approved uses shown above under "Labeled uses." This summary is informational; only a qualified prescriber can determine whether a medication is appropriate for you.
What are the most commonly reported side effects of Mexiletine?
The table above shows adverse reactions and the highest frequencies reported in placebo-controlled trials summarized in current FDA labeling for Mexiletine. Individual risk varies.
Does Mexiletine require lab monitoring?
Monitoring needs vary. Ask your healthcare provider whether any lab tests apply while taking Mexiletine.
Where does this information come from?
All clinical facts on this page were extracted from the current FDA-registered product labeling for this ingredient, published by manufacturers through NIH DailyMed. See the source link below.
Medical disclaimer: Educational content extracted from public FDA labeling. Not medical advice. Always consult a qualified healthcare professional before starting, stopping, or changing any medication.