The use of carvone in consecutive patch testing

BACKGROUND: Carvone (l-carvone) is a mint-tasting flavour additive that most of us is exposed to and can cause allergic contact reactions. OBJECTIVES: To analyse the frequency and the relevance of positive carvone reactions in a dermatitis population. METHOD: A retrospective analysis of dermatitis patients consecutively tested with carvone from 2017 to 2021. Data were retrieved from the department's patch-test database. RESULTS: Of 3554 patients tested with carvone, 28 (0.79%) had a positive reaction. Carvone-positive patients had higher mean age, were significantly more likely female (p < 0.001) and had often an intraoral/lip involvement (p < 0.001). In the carvone-positive group, 50% (n = 14) had a relevant reaction, and in 4 of 14, the relevance was first revealed after test reading. Of the carvone-positive patients, 18 of 28 did not have a coexisting allergy to a fragrance/flavour allergen and of these 44% had a relevant allergy. CONCLUSIONS: The study suggests that a significant fraction of relevant carvone contact allergies may be overlooked if the allergen is not tested. Furthermore, as the exposure is widespread, inclusion of carvone in the Swedish baseline series may be justified even if the contact allergy prevalence is below 1%