Lidocaine Dose Calculator
Calculate maximum allowable subcutaneous lidocaine dose in mg and mL from patient weight and concentration.
What Is the Maximum Lidocaine Dose?
Lidocaine is a widely used local anesthetic for subcutaneous infiltration, wound repair, and minor procedures. Without epinephrine, the standard maximum dose is 4.5 mg per kilogram of body weight, with an absolute cap of 300 mg. Exceeding this limit raises the risk of lidocaine toxicity, including central nervous system and cardiac effects. For broader local anesthetic dosing, see the Local Anesthetic Calculator.
How Lidocaine Dose Is Calculated
Maximum dose in milligrams equals the lesser of 4.5 times patient weight in kilograms or 300 mg. Volume in milliliters depends on solution concentration: multiply 4.5 by weight divided by 10, then divide by the concentration percentage. The final volume is the smaller of that weight-based volume and the volume implied by the milligram cap (dose mg divided by concentration percent times 10).
Choosing Lidocaine Concentration
Common concentrations range from 0.25% to 4%. Lower concentrations allow a larger volume for the same milligram dose, which can help spread anesthesia over a wider area. Higher concentrations deliver the same dose in less volume but require careful measurement. Always confirm the vial label and use appropriate syringe markings before infiltration.
Frequently Asked Questions
What is the maximum lidocaine dose without epinephrine?
The standard limit is 4.5 mg/kg, capped at 300 mg total regardless of body weight. Solutions with epinephrine allow higher doses because vasoconstriction slows systemic absorption.
How do I convert lidocaine dose from mg to mL?
Divide the dose in milligrams by concentration percent times 10. For example, 225 mg of 1% lidocaine equals 22.5 mL because 225 divided by (1 times 10) equals 22.5.
Why is there a 300 mg absolute maximum?
Even in large patients, 300 mg is the accepted ceiling for plain lidocaine without epinephrine. The weight-based formula may exceed this value, so the calculator applies whichever limit is lower.
Does epinephrine change the maximum dose?
Yes. Lidocaine with epinephrine typically allows up to 7 mg/kg with a higher absolute cap. This calculator applies only to plain lidocaine without epinephrine.
What are signs of lidocaine toxicity?
Early symptoms include perioral numbness, tinnitus, and dizziness. Severe toxicity can cause seizures, hypotension, and cardiac arrhythmias. Stay within recommended dosing and monitor patients after large infiltrations.
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