Both type I and type IV allergic reactions associated with corticosteroids have been reported in the literature.  Due to drug itself, the excipients making up the drug, or both?

Corticosteroids have been classified into 5 different categories based on their structural and chemical properties:

Group	Agents
A	Hydrocortisone Methylprednisolone Prednisolone
B	Budesonide Triamcinolone
C	Betamethasone Dexamethasone
D1	Mometasone furoate Fluticasone propionate

Cross-reactivity outside of these groups has only really been seen with group D2, which includes only lesser known steroids eg hyrdocortisone 17 butyrate, and group A.  Budesonide has also been described to exhibit some cross-reactivity with group D2, due to a stereoisomer, rather than its group conformation.  There is also some cross-reactivity with sex hormones, although the clinical significance is unclear – there is a type of cyclical dermatitis which is thought to be related to endogenous progesterone sensitivity.

[Allergy. 2009 Jul;64(7):978-94. doi: 10.1111/j.1398-9995.2009.02038.x]