Background: Corticosteroids may cause immediate or delayed hypersensitivity. In 1989, based on structural and clinical characteristics, we put forward a classification of corticosteroids into four cross-reacting groups, namely group A, B, C, and D, the latter later subdivided into two subgroups, i.e. D1 and D2. The constituents on the D-ring of the corticosteroid-molecule are considered to have a central role for binding to skin proteins and for cross-reactions patterns; however, halogenation of the molecules is also interfering.
Objective: To study the clinical data and analyse simultaneous positive reactions obtained in a large group of corticosteroid-allergic patients.
Methods: Patch tests were performed with the baseline series, to which hydrocortisone butyrate and prednisolone caproate were added, as well as with the corticosteroids to which the patients had been exposed. Three hundred and forty subjects with a presumed or proven corticosteroid allergy were further investigated with an extended series containing 72 molecules.
Results: Out of 11 596 patients investigated, 315 subjects reacted positively to at least 1 corticosteroid-molecule, with most of them presenting with multiple positive reactions.
Conclusion: A prevalence of corticosteroid allergy of 2.7% was found. Despite validity of the ABCD (sub)classification in many cases, possible adjustments may have to be considered.