ABSTRACT
BACKGROUND: Allergic contact dermatitis (ACD) to lidocaine is rising in prevalence. This is due to a growing number of over-the-counter (OTC) products containing topical amide and ester anesthetics. The phenomenon poses a real threat to the authors' surgical anesthetic options. OBJECTIVE: To investigate the epidemiology of topical anesthetic ACD in British Columbia, Canada and provide an approach for clinicians to deal with this problem. MATERIALS AND METHODS: A retrospective chart review of 1,819 patients who underwent patch testing at the University of British Columbia Contact Dermatitis Clinic between January 2009 and June 2013 was completed. The authors also performed a detailed review of Canadian OTC preparations containing lidocaine in 2013. RESULTS: The prevalence of ACD to local anesthetics is significant at 2.4%. The most common allergen is benzocaine (45%) followed by lidocaine (32%) and dibucaine (23%). CONCLUSION: The proportion of ACD caused by lidocaine is higher than expected. This is likely secondary to an increase in OTC medicaments containing lidocaine. Patients who are patch test-positive to a local anesthetic should be challenged intradermally to confirm clinical relevance. Because ACD is a delayed Type IV hypersensitivity reaction (localized dermatitis), the risk of anaphylaxis is not a concern.