Background: Adverse reactions from lidocaine are commonly reported. When allergy is suspected, patients may be referred for specific skin testing to confirm the association of their clinical findings.
Objective: We aimed to investigate 13 cases of suspected lidocaine allergy to analyze if positive patch results restricted future use as an injectable local anesthetic.
Methods: A prospective study was conducted from March 2013 to September 2014 at 2 academic hospital-based patch test clinics in Toronto. Patients were tested to the North American Contact Dermatitis Group standard series (Smart Practice, Phoenix, AZ) and, if suspicion for lidocaine allergy was high, a local anesthetic series (Chemotechnique Diagnostics, Malmö, Sweden) was added. Intradermal skin testing to local anesthetics below irritant concentrations was subsequently conducted in lidocaine-positive patients. If negative, a subcutaneous challenge with 1% lidocaine was done.
Results: Thirteen of 756 patients patch tested were positive to lidocaine. Seven patients had relevant reactions to over-the-counter products containing lidocaine, 2 reacted to subcutaneous lidocaine, and 4 had incidental findings. There were no patients with positive results to intradermal testing. Three patients had delayed reactions to the subcutaneous challenge.
Conclusions: Patients with positive patch tests to lidocaine and negative results to intradermal testing and subcutaneous challenge may be safe to use lidocaine as an injectable local anesthetic in the future.