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Background: Corticosteroid allergy is a complication of topical therapy detected by patch-testing with corticosteroid allergens., Objective and Methods: Ten-year retrospective review to study the prevalence and patterns of corticosteroid allergy in Thai patients., Results: Of 882 patients who were patch-tested, 29 (3.29%) had allergic reactions to corticosteroids. Of these 29 patients, 17 (58.62%) had positive reactions to one corticosteroid, and 12 (41.38%) reacted to multiple corticosteroids. Rates of reaction to corticosteroid groups ranged from 31.03 to 80.95%. Concomitant reactions between groups were noted. The prevalence of topical corticosteroid allergy (using two screening allergens, tixocortol pivalate and budesonide) was 2.27% (20 of 882). Testing with additional steroid allergens in suspected cases increased the prevalence to 3.29%. Tixocortol pivalate detected 51.72% of corticosteroid-allergic cases, and budesonide detected 24.14%. Combining both tixocortol and budesonide detected 68.97% of cases., Conclusion: Corticosteroid allergy is found to multiple corticosteroids, and concomitant reactions occur across groups. Group D1 corticosteroid esters produced a higher positive reaction rate (61.9%) than groups D2 (52.38%) and A (51.72%). This may be due to different prescribing habits or the easy access to D1 corticosteroids sold over the counter by pharmacies in Thailand.

Patch test results obtained with corticosteroid allergic patients tested with a large corticosteroid series validated the earlier classification of corticosteroid molecules in four groups of cross-reacting molecules: i.e., group A (hydrocortisone type), group B (acetonides), group C (betamethasone type-non esterified) and group D (esters). The latter group can now be subclassified into 2 groups, i.e., group D1 (halogenated and with C16 substitution) and group D2 (the "labile" prodrug esters without the latter characteristics).