INTRODUCTION: Corticosteroids may cause delayed hypersensitivity. On the basis of structure, the following 4 groups of corticosteroids are recognized: A, B, C, and D (subdivided into D1 and D2). More recently, a newer classification system subdivides corticosteroids into groups 1, 2, and 3. Cross-reactions are unpredictable. The objective of this study was to describe positive patch test and co-reaction patterns to corticosteroids. METHODS AND RESULTS: A retrospective analysis of 17,978 patients patch tested by the North American Contact Dermatitis Group between 2007 and 2014 was performed. Corticosteroids tested during this period included the following: tixocortol-21-pivalate 1.0% petroleum (pet), budesonide 0.1% pet, triamcinolone acetonide 1.0% pet, desoximetasone 1.0% pet, clobetasol-17-propionate 1.0% pet, and hydrocortisone-17-butyrate (HC-17-B) 1.0% (pet and alcohol). Overall, 4.12% (n = 741) of patients had 1 or more positive reactions to corticosteroids. Tixocortol-21-pivalate positivity was the most common (2.26%), followed by budesonide (0.87%), HC-17-B (0.43%), clobetasol-17-proprionate (0.32%), and desoximetasone (0.16%). Reaction strength was strong (++ or +++) in almost twice as many tixocortol and budesonide reactions (>64%) as compared with the other 3 corticosteroids (<34.5%). Of the patients with positive corticosteroid reactions (n = 741), most (70.7%) had sensitivity to only 1 corticosteroid. Co-reactivity was highest between desoximetasone and budesonide. CONCLUSIONS: Sensitivity to corticosteroids is important. Consistent with other studies, the highest frequency of corticosteroid positivity was seen in group A (tixocortol-21-pivalate), followed by group B (budesonide) and D2 (HC-17-B). Co-reactivity varied; more studies are needed to fully understand structural cross-reactivity.