Impact of Lidocaine Concentration on Analgesic Efficacy and Adverse Events in Dermatologic Infiltrative Anesthesia

Introduction: Infiltrative anesthesia with lidocaine plays a vital role in pain management during dermatologic procedures, ensuring patient comfort throughout the process. Objective: We aimed to investigate the correlation between three different concentrations of lidocaine (2% lidocaine with 1:100,000 epinephrine diluted at ratios of 1:2, 1:4, and 1:6) used in infiltrative anesthesia and their analgesic efficacy and adverse effects in dermatologic procedures. Methods: This study employed a randomized design, with 240 patients assigned to receive varying concentrations of lidocaine with epinephrine (2% lidocaine  with 1:100,000 epinephrine diluted at ratios of 1:2, 1:4, or 1:6) during 7 common dermatologic procedures: punch biopsy, excisional biopsy, CO2 laser biopsy, surgical excision, CO2 laser excision, fractional CO2 laser treatment, and filler injection. Total lidocaine dosage and patient comfort assessments were recorded for each participant. Results: All 3 lidocaine concentrations demonstrated comparable analgesic efficacy during the procedures, as measured by visual analog scale scores. The 1:6 dilution group required a significantly lower lidocaine dose, with a 69.3% reduction compared to the 1:4 dilution group and an 87.5% reduction compared to the 1:2 dilution group (p < 0.001). The 1:6 dilution group experienced significantly less pain during injection than that of the 1:4 dilution group and the 1:2 dilution group (p < 0.001). Conclusion: Lidocaine 2% with 1:100,000 epinephrine at dilutions ranging from 1:2 to 1:6 for infiltrative anesthesia in dermatologic procedures provided similar analgesic efficacy. Importantly, the 1:6 dilution significantly reduced both injection pain and total lidocaine dosage. More studies are required to confirm our results.