The effect of systemic corticosteroid therapy on eczematous patch test reactions was studied in 20 subjects. Fourteen subjects continued to develop positive reactions to standard concentrations of allergens while receiving a daily oral dose of 40 mg prednisone. In six other subjects strongly positive patch test reactions were reversed during treatment with prednisone. Other evidence of corticosteroid effect included changing patterns of reaction to a series of graded dilutions of allergens and the delayed appearance of positive reactions in some subjects.
O'Quinn SE, Isbell KH. Influence of Oral Prednisone on Eczematous Patch Test Reactions. Arch Dermatol. 1969;99(4):380-389. doi:10.1001/archderm.1969.01610220008002