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.