Comparison of the onset, depth, and duration of cutaneous anesthesia between topical 10% lidocaine and EMLA creams: a randomized, intraindividual, comparative trial.

Background: The eutectic mixture of local anesthetics (EMLA) is an effective cutaneous anesthetic, although its application is time consuming and poses a risk of methemoglobinemia. Currently, the efficacy of topical 10% lidocaine cream is unclear.

Objective: To compare the onset, anesthesia depth, and duration of topical 10% lidocaine and EMLA cream.

Methods: The randomized, split-body, comparative trial performed on 40 participants who received a topical 10% lidocaine cream or EMLA on forearms for 15-150 min. Pain was stimulated using a 21-gauge needle insertion and evaluated with the Verbal Pain Score. Adverse effects were recorded.

Results: EMLA conferred significantly better efficacy than 10% lidocaine (p < .001). For acceptable pain at 4-mm depth, the minimal application times were 40.88 and 45.38 min of EMLA and 10% lidocaine creams, respectively. With 60/120-min application, the maximal needle-insertion depths with acceptable pain were 6.61/9.47 mm (EMLA) and 6.01/8.94 mm (10% lidocaine). EMLA's anesthetic effect showed an early increase after removal which was sustained for 60-90 min. Both creams caused adverse effects, with EMLA showing higher proportions, although the differences were statistically insignificant.

Conclusion: The efficacy of EMLA was superior to 10% lidocaine cream, especially regarding anesthesia onset and duration.