Lidocaine Dose Calculator

Created by Mariamy Chrdileli
Reviewed by Łucja Zaborowska, MD, PhD candidate and Steven Wooding
Last updated: May 03, 2022

We created this lidocaine dose calculator to help you determine the maximum allowable subcutaneous dose of lidocaine.

Lidocaine is the most commonly used local anesthetic in many medical specialties. Although lidocaine has a good safety margin before it causes toxicity, it is crucial to be aware of the maximum allowable subcutaneous dose to avoid serious health complications. Whether you're a medical professional or a patient, come along and learn how to calculate the max dose of lidocaine, how lidocaine works, how the lidocaine dose calculator works, who should not use lidocaine, and more!

Do not use the lidocaine dose calculator as the primary guide for dosing. The calculator only helps you determine the maximum allowable subcutaneous dose of lidocaine.

What is lidocaine used for and how does it work?

Lidocaine, sometimes referred to as lignocaine, is a local anesthetic mainly used to prevent or alleviate pain caused by uncomfortable medical procedures – the physicians also use it to suppress abnormal rhythms of the heart (cardiac arrhythmias). This amino amide-type local anesthetic works by blocking the nerves from sending pain signals. The effects of lidocaine usually last at least 20 minutes, and it's half-life (amount of time it takes for a drug's concentration in the blood plasma to reduce by half) is around 90-120 minutes.

Lidocaine is mainly well-tolerated, with hypersensitivity reaction being a rare occasion. However, it can reach toxic blood levels, causing direct nerve toxicity at the injection site, as well systemic toxicity affecting the brain.

Although lidocaine toxicity depends not only on the total dose administered but also on the absorption rate, it is essential to be cautious to avoid administering a toxic dose of lidocaine.

Lidocaine dosing

Calculating the maximum allowable subcutaneous lidocaine dose (without epineprhrine) according to weight is relatively straightforward.

For calculating the maximum allowable dose in mg, use the formula below:

dose(mg) = 4.5 × weight

where:

  • dose(mg) – Maximum allowable subcutaneous lidocaine dose according to your weight in mg;
  • 4.5 – Represents maximum allowable subcutaneous lidocaine dose per kg (i.e., mg/kg); and
  • weight – Your weight in kg.

For calculating maximum allowable dose in ml, use the following formula:

dose(ml) = 4.5 × (weight / 10) × (1 / concentration)

where

  • dose(ml) – Maximum allowable subcutaneous lidocaine dose according to your weight in ml; and
  • concentration – Lidocaine concentration percentage.

How does lidocaine max dose calculator work?

Now that you know how to calculate the maximum allowable subcutaneous dose of lidocaine, let's discuss how the lidocaine dose calculator works:

  1. Enter the weight in the unit of your convenience.
  2. Chose concentration of lidocaine (0.25%, 0.5%, 0.75, 1%, 1.5%, 2%, 3%, or 4%).
  3. Voila! The calculator will determine the maximum allowable subcutaneous dose of lidocaine in mg and ml.

FAQ

What is lidocaine?

Lidocaine is a local anesthetic, often used to either prevent or treat pain and discomfort from medical procedures, such as surgery, needle punctures, or insertion of the breathing tube.

How do I calculate max allowable dose of subcutaneous lidocaine based on weight?

To order to calculate the max allowable dose of subcutaneous (subQ) lidocaine:

  1. Take the maximum allowable dose of lidocaine, which is 4.5 mg/kg;
  2. Multiply 4.5 by your weight in kg;
  3. That's it! You have calculated the maximum allowable subQ dose of lidocaine in mg.

How do I calculate maximum allowable volume of subcutaneous lidocaine, if my weight is 75 kg?

To calculate the maximum allowable volume of subcutaneous lidocaine:

  1. Divide your weight in kg by 10.
  2. Divide 1 by the lidocaine concentration (e.g., 0.25%).
  3. Multiply the numbers computed in Step 1 and Step 2.
  4. Multiply the result by the max allowable subcutaneous dose of lidocaine based on weight (ml), which is 4.5.
  5. That's all! 135 ml is the maximum allowable subcutaneous dose of lidocaine based on your weight.

Who should not use lidocaine?

Patients with the following conditions should avoid taking lidocaine:

  • Hypersensitivity to amide-type local anesthetics;
  • Impaired lung function;
  • Methemoglobinemia;
  • Glucose-6-phosphate dehydrogenase deficiency;
  • Wolff-Parkinson-White Syndrome;
  • Adams-Stokes syndrome;
  • Heart block;
  • Cardiogenic shock; and
  • Liver problems.
Mariamy Chrdileli
Weight
lb
Concentration
0.25%
Max allowable subQ dose
ml
mg
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