Lidocaine Dosing for Laceration Repair

Dosing Guidelines

The American Academy of Dermatology recommends a maximum dose of lidocaine without epinephrine of 4.5 mg/kg of body weight for adults, with a general recommendation not to exceed 300 mg total 1
For children, the maximum recommended dose of lidocaine without epinephrine is 1.5-2.0 mg/kg 1
For infants younger than 6 months, doses of amide local anesthetics should be decreased by 30% 2

Lidocaine is commonly available in concentrations of 1% (10 mg/mL) and 2% (20 mg/mL) 1, 2

For optimal anesthesia, allow 1-2 minutes after injection before beginning the procedure 1
Lower doses should be used in very vascular areas to prevent rapid systemic absorption 2

Calculate the maximum allowable volume before administration to avoid toxicity 1, 2
Signs of local anesthetic systemic toxicity (LAST) include circumoral numbness, facial tingling, slurred speech, metallic taste, auditory changes, and hallucinations 1
More severe manifestations include seizures, central nervous system depression, and cardiac failure 1
To prevent toxicity, avoid intravascular injection 1
Using multiple forms of lidocaine simultaneously should be avoided 3

For patients with true lidocaine allergy, consider ester-type local anesthetics (minimal cross-reactivity with amide anesthetics) 1
1% diphenhydramine can be used as an alternative, though it has a longer onset of action and limited efficacy 1
Bacteriostatic saline (0.9% benzyl alcohol in normal saline) can be used as an alternative 1
Topical anesthetics like LET (lidocaine, epinephrine, tetracaine) can be effective for open wounds, providing anesthesia in 10-20 minutes 3

Exceeding maximum recommended doses, especially when treating multiple lacerations, can lead to toxicity 1
Not allowing sufficient time for onset of anesthesia before beginning the procedure can result in patient discomfort 1
The dose of local anesthesia needed for most dermatologic procedures is well below the manufacturer-recommended maximum, making anesthetic toxicity in the dermatologic setting extremely rare 1