What is the added value of patch testing with 30 fragrance allergens in addition to the European Baseline series?

Background: Patch testing with the fragrance allergy markers in the European baseline series (EBS) does not identify all patients with fragrance allergy. Hydroperoxides of linalool and limonene have been shown to be useful allergens in detecting fragrance sensitization. Objectives: To evaluate the added value of testing with 30 fragrance allergens in addition to the EBS. Methods: All patients with suspected fragrance allergy who underwent patch testing at the Amsterdam University Medical Centers between November 2019 and January 2021 to the EBS and fragrance series were included. Results: Of 323 patients tested, 162 (50.2%) were found to be fragrance sensitized. The most sensitizing single allergens were the hydroperoxides of linalool (1.0 and 0.5% pet.) and limonene (0.3 and 0.2% pet.). Testing with the hydroperoxides of linalool and limonene identified 62 fragrance-sensitized patients (38.3%) who could not be detected by the common fragrance markers. Of all fragrance-sensitized patients, 21 (13.0%) would have been missed when not testing with the fragrance series. Conclusions: Patch testing with the fragrance series in addition to the EBS is valuable. To reduce the risk of false-negative reactions, it is advisable to test the hydroperoxides of linalool and limonene.