What Is Mexiletine? Uses, Dosage, and What You Need to Know in 2026

If you've recently been prescribed mexiletine or are trying to understand a loved one's treatment, you've come to the right place. This guide explains what mexiletine is, what it's used for, how it works, how to take it, and everything else you need to know as a patient in 2026.

What Is Mexiletine?

Mexiletine hydrochloride (formerly brand name Mexitil, now discontinued) is a prescription oral medication classified as a Class 1B antiarrhythmic agent. It works by blocking sodium channels in heart cells, helping to stabilize abnormal heart rhythms. It is structurally similar to lidocaine — the local anesthetic used in dental offices and emergency rooms — and can be thought of as "oral lidocaine" because it does the same job but can be taken as a capsule.

Mexiletine is available only as a generic in the United States, in three capsule strengths: 150 mg, 200 mg, and 250 mg. Multiple manufacturers produce it, including Teva and Lannett.

What Is Mexiletine Used For?

Mexiletine has one FDA-approved indication and several well-recognized off-label uses:

FDA-Approved Use: Ventricular Arrhythmias

Mexiletine is FDA-approved for treatment of documented, life-threatening ventricular arrhythmias — abnormal heart rhythms originating in the lower chambers (ventricles) of the heart. Specifically, it is used for:

Sustained ventricular tachycardia (VT) — a dangerously fast heart rhythm starting in the ventricles

Premature ventricular contractions (PVCs) that are symptomatic and life-threatening

Mexiletine is reserved for serious cases where the arrhythmia is life-threatening. It is not intended for mild or asymptomatic arrhythmias.

Off-Label Uses of Mexiletine

Long QT Syndrome Type 3 (LQT3): AHA/ACC/HRS guidelines recommend mexiletine for LQT3 patients with Torsades de pointes. It shortens the QT interval by correcting the abnormal sodium current in LQT3.

Myotonic Dystrophy / Myotonia: Used to reduce muscle stiffness and pain in myotonic dystrophy. In Europe, the brand NaMuscla contains mexiletine specifically approved for this indication.

Diabetic Neuropathy / Chronic Pain: Mexiletine's sodium channel-blocking effects can reduce nerve pain in some patients with diabetic peripheral neuropathy, though it's less commonly used for this purpose given its cardiac side effect profile.

Mexiletine Dosage: What to Expect

Mexiletine dosing is individualized based on your response and tolerability. Typical dosing:

Starting dose: 200 mg every 8 hours (when rapid control is not needed)

Loading dose (rapid control): 400 mg followed by 200 mg 8 hours later

Maintenance: 200–300 mg every 8 hours is effective for most patients; may increase to 400 mg q8h if needed

12-hour dosing: Once stable on 300 mg or less every 8 hours, some patients can switch to the same total daily dose given every 12 hours

Dose adjustments: Made in 50-100 mg increments no more than every 2-3 days

How to Take Mexiletine

Take with food or antacid: Always take mexiletine with a meal, milk, or an antacid to prevent nausea and heartburn

Space doses evenly: For 3x daily dosing, aim for every 8 hours (e.g., 6 AM, 2 PM, 10 PM)

Don't stop abruptly: Abrupt discontinuation can worsen arrhythmias

Keep appointments: Regular EKG monitoring and lab tests are needed throughout therapy

Who Should Not Take Mexiletine?

Mexiletine is contraindicated in:

Patients with cardiogenic shock

Patients with pre-existing second- or third-degree AV block (without a pacemaker)

Patients with known allergy to mexiletine or lidocaine

For more detail, read our guides on mexiletine side effects and how mexiletine works.