Contact allergy to lidocaine.

Area of Science:

• Dermatology
• Allergology
• Anesthesiology

Background:

• Lidocaine is a widely used local anesthetic.
• Contact allergy to local anesthetics is uncommon but can cause significant reactions.

Observation:

• Two patients presented with contact allergy to lidocaine.
• Reactions occurred after topical application of lidocaine.

Findings:

• Both patients exhibited cross-reactivity to other amide-type local anesthetics.
• One patient reacted to bupivacaine, mepivacaine, and prilocaine.
• The other patient reacted only to mepivacaine.
• Cross-reactivity was also noted with cinchocaine, an ester-type anesthetic.
• Lidocaine metabolites, o-toluidine and mxylidine, did not elicit a reaction.

Implications:

• These findings highlight the potential for cross-reactivity among different classes of local anesthetics.
• Clinicians should consider alternative anesthetic agents in patients with known lidocaine allergy.
• Further investigation into the mechanisms of cross-reactivity is warranted.