What the label lists and what reports show
Mexiletine side effects
Mexiletine's FDA label lists its adverse reactions in its own words. FAERS holds 420 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is fatigue (32 reports).
- Generic listed
Check it at the source: the mexiletine FDA label on DailyMed (effective May 14, 2026, Macleods Pharmaceuticals Limited); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsMexiletine hydrochloride commonly produces reversible gastrointestinal and nervous system adverse reactions but is otherwise well tolerated. Mexiletine has been evaluated in 483 patients in one month and three month controlled studies and in over 10,000 patients in a large compassionate use program. Dosages in the controlled studies ranged from 600 to 1200 mg/day; some patients (8%) in the compassionate use program were treated with higher daily doses (1600 to 3200 mg/day). In the three month controlled trials comparing mexiletine to quinidine, procainamide and disopyramide, the most frequent adverse reactions were upper gastrointestinal distress (41%), lightheadedness (10.5%), tremor (12.6%) and coordination difficulties (10.2%). Similar frequency and incidence were observed in the one month placebo-controlled trial. …
Table 2: Comparative Incidence (%) of Adverse Events Among Patients Treated with…
This table is printed in the MEXILETINE HYDROCHLORIDE label published by Ingenus Pharmaceuticals, LLC of July 28, 2023; the label quoted above does not print one.
| Reaction | Mexiletine N = 430 | Quinidine N = 262 | Procainamide N = 78 | Disopyramide N = 69 |
|---|---|---|---|---|
| Palpitations | 4.3 | 4.6 | 1.3 | 5.8 |
| Chest Pain | 2.6 | 3.4 | 1.3 | 2.9 |
| Angina/Angina- like Pain | 1.7 | 1.9 | 2.6 | 2.9 |
| Increased Ventricular Arrhythmias/PVC's | 1 | 2.7 | 2.6 | - |
| Nausea/Vomiting/Heartburn | 39.3 | 21.4 | 33.3 | 14.5 |
| Diarrhea | 5.2 | 33.2 | 2.6 | 8.7 |
| Constipation | 4 | - | 6.4 | 11.6 |
| Changes in Appetite | 2.6 | 1.9 | - | - |
| Abdominal Pain/Cramps/Discomfort | 1.2 | 1.5 | - | 1.4 |
| Dizziness/Lightheadedness | 18.9 | 14.1 | 14.1 | 2.9 |
| Tremor | 13.2 | 2.3 | 3.8 | 1.4 |
| Coordination Difficulties | 9.7 | 1.1 | 1.3 | - |
| Changes in Sleep Habits | 7.1 | 2.7 | 11.5 | 8.7 |
| Weakness | 5 | 5.3 | 7.7 | 2.9 |
| Nervousness | 5 | 1.9 | 6.4 | 5.8 |
| Fatigue | 3.8 | 5.7 | 5.1 | 1.4 |
| Speech Difficulties | 2.6 | 0.4 | - | - |
| Confusion/Clouded Sensorium | 2.6 | - | 3.8 | - |
| Paresthesias/Numbness | 2.4 | 2.3 | 2.6 | - |
| Tinnitus | 2.4 | 1.5 | - | - |
| Depression | 2.4 | 1.1 | 1.3 | 1.4 |
| Blurred Vision/Visual Disturbances | 5.7 | 3.1 | 5.1 | 7.2 |
| Headache | 5.7 | 6.9 | 7.7 | 4.3 |
| Rash | 4.2 | 3.8 | 10.3 | 1.4 |
| Dyspnea/ Respiratory | 3.3 | 3.1 | 5.1 | 2.9 |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
Source: FDA drug label, Macleods Pharmaceuticals Limited, effective May 14, 2026 (SPL set a61a07f6-0b48-4dcd-ad42-5d90f6e69ab1), via openFDA; the full label on DailyMed
What do FAERS reports show?
420 reports list mexiletine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 76 are coded as a death and 255 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 22 reactions below, 6 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Mexiletine: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions