Depth and duration of skin analgesia to needle insertion after topical application of EMLA cream.

We have determined the depth and duration of analgesia to needle insertion after topical application of EMLA cream (Eutectic Mixture of Local Analgesics). EMLA was applied for 30, 60, 90 and 120 min and the sensory and pain threshold depths were determined before analgesia (1.0 and 1.9 mm, respectively) and up to 4 h after the cream was removed from the skin. The maximal depth of analgesia (approx. 5 mm) was observed 30 min after a 90-min application and during the 60-min period after a 120-min application of EMLA cream, for both sensory and pain thresholds. For application times shorter than 120 min, the depth of analgesia increased during the period after removal of the cream. This suggests new guidelines for the use of this topical analgesic.