Calculate maximum safe lidocaine dose by weight with or without epinephrine. Includes toxicity thresholds, volume conversions, and LAST emergency reference.
The Lidocaine Dose Calculator determines the maximum safe dose of lidocaine (lignocaine) based on patient weight, epinephrine co-administration, procedure type, and patient factors. Lidocaine is the most commonly used local anesthetic worldwide, employed in infiltration anesthesia, nerve blocks, epidural analgesia, topical mucosal anesthesia, and tumescent liposuction.
The maximum recommended dose differs dramatically depending on whether epinephrine is added: 4.5 mg/kg without epinephrine versus 7 mg/kg with epinephrine. For tumescent liposuction, doses up to 55 mg/kg have been used safely due to the slow systemic absorption from dilute subcutaneous infiltration. Understanding these limits is critical because lidocaine toxicity — known as Local Anesthetic Systemic Toxicity (LAST) — can progress rapidly from perioral numbness and tinnitus to seizures and fatal cardiovascular collapse.
This calculator converts between concentrations and volumes, adjusts for patient populations at higher risk (elderly, hepatic impairment, pediatric patients), provides visual dose-tracking against the maximum, and includes reference tables for toxicity recognition and emergency management including the lipid emulsion (Intralipid 20%) rescue protocol.
Lidocaine overdose can cause seizures and cardiac arrest within minutes. This calculator helps clinicians, dentists, and emergency physicians verify that planned doses stay within safe weight-based limits, convert between concentrations, and adjust for high-risk patient populations. It is especially valuable when using multiple injection sites or combining with other local anesthetics.
Max Dose (mg) = Body Weight (kg) × Max mg/kg Without Epinephrine: 4.5 mg/kg (max 300 mg) With Epinephrine: 7 mg/kg (max 500 mg) Tumescent: up to 55 mg/kg Planned Dose (mg) = Volume (mL) × Concentration (mg/mL) Concentration: 1% = 10 mg/mL, 2% = 20 mg/mL
Result: Max dose 490 mg; Planned dose 200 mg (40.8% of max); 290 mg safety margin
A 70 kg adult using lidocaine 1% with epinephrine has a maximum of 7 mg/kg × 70 kg = 490 mg. The planned 20 mL × 10 mg/mL = 200 mg, using 40.8% of the allowance with a 290 mg safety margin.
Lidocaine is supplied in concentrations ranging from 0.5% to 5%. The percentage directly converts to mg/mL by multiplying by 10: 1% lidocaine contains 10 mg/mL. A 20 mL syringe of 1% lidocaine therefore contains 200 mg total. For procedures requiring large volumes (such as field blocks or wound infiltration), lower concentrations (0.5%) allow greater volume while staying within dose limits. Higher concentrations (2%) are used when less volume is needed, such as dental blocks.
LAST occurs when plasma lidocaine levels exceed the therapeutic range. The CNS is more sensitive than the cardiovascular system, so neurological symptoms (tinnitus, metallic taste, perioral numbness) appear first. At higher levels, excitatory CNS activity causes seizures. At very high levels, both CNS depression and cardiovascular collapse occur. Risk factors for LAST include extremes of age, hepatic disease, cardiac disease (reduced clearance), pregnancy, and acidosis (which increases the fraction of ionized drug that is more toxic).
The discovery that intravenous lipid emulsion can rescue patients from local anesthetic cardiac arrest transformed emergency management of LAST. The proposed mechanism involves lipid acting as a "sink" that binds lipophilic local anesthetic molecules, reducing their myocardial concentration. The protocol calls for a 1.5 mL/kg bolus of 20% lipid emulsion followed by 0.25 mL/kg/min infusion, which can be repeated. This has saved lives in cases previously considered fatal.
The maximum dose of plain lidocaine (without epinephrine) is 4.5 mg/kg, with an absolute ceiling of 300 mg for adults. This limit exists because systemic absorption is faster without the vasoconstrictive effect of epinephrine.
Epinephrine causes local vasoconstriction, slowing systemic absorption of lidocaine. This keeps more drug at the injection site (prolonging anesthesia) and reduces peak plasma levels, allowing a higher total dose of 7 mg/kg.
Early CNS toxicity signs include perioral (around the mouth) numbness or tingling, metallic taste, tinnitus (ringing in the ears), lightheadedness, and visual disturbances. These precede more serious symptoms like seizures and cardiac arrest.
Local Anesthetic Systemic Toxicity (LAST) treatment includes stopping injection immediately, calling for help, securing the airway, giving IV lipid emulsion (Intralipid 20%) — 1.5 mL/kg bolus then 0.25 mL/kg/min infusion — and treating seizures with benzodiazepines. Avoid propofol and vasopressin.
In tumescent technique, very dilute lidocaine (0.05–0.1%) is mixed with epinephrine in large volumes of saline infiltrated subcutaneously. The extreme dilution, epinephrine, and subcutaneous tissue create very slow absorption, so peak plasma levels remain safe even at high total doses.
Yes. Elderly patients have reduced hepatic metabolism and increased sensitivity to local anesthetics. A 25% dose reduction is generally recommended, and careful monitoring for toxicity signs is essential.
Lidocaine percentage × 10 gives mg/mL. So 1% = 10 mg/mL, 2% = 20 mg/mL, 0.5% = 5 mg/mL. To find the volume for a desired dose: Volume (mL) = Dose (mg) ÷ Concentration (mg/mL).