Glucocorticoids are frequently used to treat allergic reactions. Therefore, allergic reactions to systemic glucocorticoids in particular are considered most unlikely and are not well known. We report on a 23-year-old woman with atopic dermatitis who had an anaphylactic reaction after oral administration of prednisolone. On treatment with epinephrine, antihistamines and volume symptoms resolved. Skin testing with a panel of glucocorticoids showed immediate type reactions to prednisolone, prednisolone hydrogen succinate, prednisone, and betamethasone dihydrogen phosphate. In challenge testing the patient tolerated methyl prednisolone and dexamethasone. There is increasing evidence that true allergic immediate type reactions to glucocorticoids exist. The severity of the reaction can vary from a rash to anaphylaxis. However, a patient sensitized to one or a group of glucocorticoids does not have to refrain from all types of glucocorticoids. Careful challenge testing is by far the best way to select glucocorticoids that are safe for future treatment. Clinicians should be aware that allergic reactions to glucocorticoids can occur and that worsening of symptoms does not always mean treatment failure.