AbstractBackgroundPatients are consecutively screened for contact allergy to corticosteroids with budesonide and tixocortol‐21‐pivalate in the European baseline series. Centres using TRUE Test also include hydrocortisone‐17‐butyrate. A supplementary corticosteroid patch test series is used in case of suspicion of corticosteroid contact allergy or when a marker of corticosteroid contact allergy is positive.ObjectiveThe aims were to evaluate (1) the efficacy of corticosteroids in the TRUE Test and (2) co‐sensitization patterns.MethodsThis retrospective study analysed patients patch tested with TRUE Test corticosteroids plus supplementary corticosteroid series in the period 2006–2020 at the Department of Dermatology and Allergy Centre, Odense University Hospital.ResultsOf 1852 patients tested, 119 were sensitised to TRUE Test corticosteroids and supplementary testing found additional reactions to other corticosteroids in 19 of 119 patients. TRUE Test corticosteroids gave more positive and stronger reactions compared to allergens in petrolatum/ethanol. Fourteen percent of sensitised patients were co‐sensitised to multiple corticosteroid groups. Baeck group 3 corticosteroids accounted for 9 of 16 patients not identified by TRUE Test.ConclusionsBudesonide, hydrocortisone‐17‐butyrate, and tixocortol‐21‐pivalate in combination are sensitive corticosteroid markers. In case of clinical suspicion of corticosteroid contact allergy, patch testing with supplementary corticosteroids is highly recommended.