ACLS Drugs – Lidocaine

By Mark Dzwonkiewicz, FP-C, LI | Medically reviewed by Brenda Shih, PharmD on February 19, 2025

ACLS Certification Association videos have been peer-reviewed for medical accuracy by the ACA medical review board.

Introduction to Lidocaine
Dosing
Side Effects
Drug Administration

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Summary

Article at a Glance

Lidocaine is a calcium channel blocker antiarrhythmic used in treating VF and pulseless VT.
The dosage of lidocaine is 1-1.5 mg/kg as a first dose and the second dose is half the first for a total of 3 mg/kg.
Side effects of lidocaine include hypotension, altered mental status, seizures, and slurred speech.
The provider should administer lidocaine and follow with a saline bolus.

Introduction to Lidocaine

The purpose of this article is to provide a complete, up-to-date guide on the use of Lidocaine according to current ACLS drugs guidelines. It covers when Lidocaine is indicated, recommended dosing ranges, administration techniques, and potential side effects. By presenting the latest evidence-based recommendations, this resource helps healthcare providers apply ACLS standards effectively in clinical practice.

How it Works

Lidocaine is classified as a Class I antiarrhythmic drug, meaning it acts primarily as a sodium channel blocker. By inhibiting the influx of sodium ions during the depolarization phase of the cardiac action potential, Lidocaine slows conduction and reduces excitability in cardiac tissue.

This mechanism is particularly effective against re-entrant ventricular rhythms, such as ventricular tachycardia, because it interrupts the abnormal electrical circuits responsible for sustaining these arrhythmias. By stabilizing the cardiac membrane and suppressing irregular conduction pathways, Lidocaine helps restore a more organized rhythm and supports the overall goals of ACLS in managing life-threatening ventricular arrhythmias.

Dosing

The dosing parameters for lidocaine are 1–1.5 mg/kg. Next, we’ll learn why there is such a range. Here is an example: a manufacturer’s package: 100 mg in 5mL.

Lidocaine packaging.

Lidocaine comes packaged as 100mg in 5mL.

Think about this dosing example: If I wanted to administer 1mg/kg and I wanted to use that whole ampule — the whole 100 milligrams — my patient would have to weigh 100 kg (or 220 pounds). If I gave the whole thing, 100 mg at a dosing of 1 mg/kg, my patient weighs 220 pounds.

Now, if I wanted to administer 1.5 mg to my patient and use the whole vial, all 100 mg, my patient would have to weigh 66 kg (or about 146 pounds). So what does that mean? In short, if your adult patient weighs between 146 pounds and 220 pounds, administer the whole 5 mL, or 100 mg, and you will be dosing that patient within the recommended dosing parameters of 1–1.5 mg/kg. For elderly patients, you may want to cut the dose in half. Follow your local protocols.

Drug Administration

Indications

Lidocaine is indicated in ACLS for the treatment of life‑threatening ventricular arrhythmias. It is most commonly used in the following situations:

Ventricular Fibrillation (VF) or Pulseless Ventricular Tachycardia (VT) unresponsive to defibrillation and CPR.
Stable Ventricular Tachycardia with a pulse, especially when amiodarone is unavailable or contraindicated.
As an alternative antiarrhythmic when amiodarone cannot be used due to allergy or intolerance.
In certain post‑cardiac arrest settings to suppress recurrent ventricular arrhythmias.

How We Administer Lidocaine

Keep in mind how we administer Lidocaine… [your existing content continues here, explaining routes, dosing, IV push vs infusion, etc.]

Keep in mind how we administer the medication. Remember, antiarrhythmics have to get to the heart to be effective. After you administer that medication by IV route, you follow it with a 10–20 mL syringe bolus of saline to help push that drug to the heart.

If they’re in ventricular fibrillation (VF), they have no cardiac output. Compressions provide maybe 20 or 25% of the normal cardiac output, so we have to help that medication get to the heart quickly and in sufficient concentration to cause an effect.

Side Effects

Side effects of lidocaine, based on what is published, are altered mental status, slurred speech, hypotension, and seizures. Watch for hypotension with the administration of any antiarrhythmic.

As for seizures, it is rare. However, every time I’ve administered lidocaine within the context of ACLS, my patient was at that time, almost dead, and that they had no pulse and were not spontaneously breathing. I’ve never actually seen a seizure with lidocaine, but it is something to watch for.

Read: ACLS Drugs – Epinephrine

Summary

Lidocaine has several usages in ACLS. After reading this article, you now understand the dosing information, side effects, and administration.

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