Hi-I Was Given IV Decadron Today As A Part Of

Hi-I was given IV Decadron today as a part of a " cocktail" to counteract a migraine headache associated with a severe viral infection ( a bad cold )......... I was in the ER to treat a severe cough, nausea and severe headache. I am not allergic to anything , but got a transient albeit startling reaction to the Decadron including urticaria in my scalp and extending throughout my limbs and finally groin. While severe, the reaction disappated after about 30 seconds. I've never heard of this......is this a common,reaction?