Lidocaine is a class IB antiarrhythmic drug used in the treatment of ventricular arrhythmias, specifically ventricular tachycardia and ventricular fibrillation. Lidocaine blocks cardiac sodium channels shortening the action potential and is used intravenously only for arrhythmia. Lidocaine is also used as a topical anesthetic.

Lidocaine is not recommended for prophylactic administration to suppress premature ventricular contractions or prevent ventricular tachycardia or ventricular fibrillation after an acute coronary syndrome. Lidocaine toxicity is a concern.