Sources of sensitization, cross‐reactions, and occupational sensitization to topical anaesthetics among general dermatology patients

BACKGROUND: Contact sensitization to local anaesthetics is often from topical medicaments. Occupational sensitization to topical anaesthetics may occur in certain occupations. OBJECTIVES: The aim of the study was to analyse the occurrence of contact sensitization to topical anaesthetics in general dermatology patients. PATIENTS AND METHODS: Patch testing with topical anaesthetics was carried out in 620 patients. Possible sources of sensitization and the clinical histories of the patients are analysed. RESULTS: Positive patch test reactions to one or more topical anaesthetics were seen in 25/620 patients. Dibucaine reactions were most common (20/25), and lidocaine sensitization was seen in two patients. Six patients had reactions to ester-type and/or amide-type anaesthetics concurrently. Local preparations for perianal conditions were the most common sensitizers. One patient had developed occupational sensitization to procaine with multiple cross-reactions and with concurrent penicillin sensitization from procaine penicillin. CONCLUSIONS: Dibucaine-containing perianal medicaments are the major source of contact sensitization to topical anaesthetics. Although sensitization to multiple anaesthetics can be seen, cross-reactions are possible. Contact sensitization to lidocaine is not common, and possible cross-reactions should be determined when reactions to lidocaine are seen. Occupational procaine sensitization from veterinary medicaments is a risk among animal workers.