Expanding Patch Testing Beyond the Baseline Series: Usefulness of Customized Antimicrobials, Vehicles, and Cosmetics Series.

Background: Testing cosmetics and their ingredients is essential to avoid missing relevant allergens and to monitor fluctuating incidence of hypersensitivity.
Objective: The aim of this study was to review the usefulness of patch testing with a customized antimicrobials, vehicles, and cosmetics (AVC) series over 15 years at a single Canadian site.
Methods: Between January 1, 2005, and December 31, 2019, patients suspected of having cosmetics allergy were patch tested with a 40-allergen AVC series in addition to the North American Contact Dermatitis Group standard screening series. We reviewed the patch test results of 2868 patients.
Results: We consecutively patch tested with the baseline series 6103 patients, of which 2868 (47%) were also tested with the AVC series. Of 53 different allergens that were tested at some point, 26 remained in the series throughout the 15-year span. The most common positive allergens were thimerosal (4.52%), polyvidone-iodine (2.25%), propolis (2.06%), sodium metabisulfite (1.94%), dodecyl gallate (1.53%), carmine (1.10%), lauryl glucoside (1.01%), sandalwood oil (0.7%), and tert-butylhydroquinone (0.7%).
Conclusions: Although the expansion of the North American Contact Dermatitis Group standard screening series has decreased the yield from the AVC series from 21.1% to 13.9%, it still remains a useful adjunct for patients suspected of having cosmetics or disinfectants allergy.