Contact allergy to local anaesthetics–value of patch testing with a caine mix in the baseline series

Abstract

Background Contact allergy to local anaesthetics is relatively common. Patch testing with benzocaine in the European baseline series is recommended for diagnosis, even though a caine mix has been previously suggested to be superior. Objectives To assess the frequency and patterns of contact allergy to local anaesthetics by using a caine mix (benzocaine, tetracaine, and cinchocaine) in the baseline series, and evaluate its efficiency as compared with benzocaine alone. Methods We reviewed the results of 2736 patch tests performed between 2000 and 2010, identifying patients with positive reactions to caine mix or to one of seven local anaesthetics. Results One hundred and twelve patients (4.1%) had at least one allergic reaction to local anaesthetics; 86 were tested with all seven local anaesthetics, resulting in 71 reactions in 53 patients. Cinchocaine gave the most reactions (50.7%); these occurred as a single reaction in 83.3% of patients, mostly with current or past relevance (97%). Benzocaine represented 22.5% of reactions, many of which were non‐relevant (44%) or resulting from cross‐reactions with para‐compounds. Conclusions Almost 70% of allergic reactions to local anaesthetics would have been missed if benzocaine had been used as a screening allergen. This study supports a recommendation to replace benzocaine with a caine mix containing cinchocaine in the baseline patch test series.

European Surveillance System on Contact Allergies (ESSCA): results with the European baseline series, 2013/14

“…Despite this, the reaction prevalence is low in the present results, and even lower than in the previous analysis of 2004 data [0.6% (95% CI: 0.5–0.7%) vs. 1.1% (95% CI: 0.8–1.4%)]. The use of a suitable mix of ‘caines’, including cinchocaine (syn; dibucaine), as a possible replacement of benzocaine in the EBS should be considered, in particular, as benzocaine as screening marker has been found to miss 70% of contact allergies to local anaesthetics …”

Baboon syndrome caused by anti‐haemorrhoidal ointment

“…However, concomitant sensitization to both groups has been reported . In our patient, simultaneous reactivity to cinchocaine and tetracaine may be attributable to concomitant sensitization, because of the use of multiple perianal ointments during the previous years . According to the patch test results only, we cannot establish which drug was responsible for the baboon syndrome.…”

“…Systemic allergic dermatitis caused by local anaesthetics is quite uncommon, and has been mainly attributed to cinchocaine (dibucaine) . We report an unusual case of baboon syndrome induced by an anti‐haemorrhoidal ointment, most likely attributable to tetracaine (amethocaine) in a patient previously sensitized both to amide and ester local anaesthetics by skin contact.…”

The Rare Case of a Probably True IgE-Mediated Allergy to Local Anaesthetics

“…In our own study from 2006, we could only confirm 2/36 cases [7]. In contrast, type IV allergy to LA is a relative common finding, and therefore, LAs are included in standard patch test series [8]. …”