Severe hives from unknown source
My almost 4 year old son (severely allergic to peanuts, cashews and shellfish) had a bout of severe hives after eating breakfast yesterday morning. He ate the same foods he's always eaten (a Kellogg's Nutrigrain cereal bar and rice milk), and within an hour had the most severe case of hives he's ever had. Benedryl didn't keep them away, nor did Hydroxyzene. We ended up getting the steroid, Prelone, to chase the hives away. He had no other symptoms (no tongue swelling, etc.) It took a good 6 hours for the hives to go away, only to come back this morning in full force. The Prelone seems to have taken full effect today. We saw the allergist today who said to continue a 5 day treatment of the steroid and an antihistamine.
I've called Kelloggs to report the hives, and they assured me there are no peanuts or nuts of any kind in the production of the Nutrigrain bars. They're willing to test the bars against the ingredient listing on the side of the box and will be sending me a mailing envelope to mail back the remaining bars. I have yet to call on the rice milk, but he's been drinking it for 3 years now with no problems.
Our allergist thinks there may be yet another food that our son is severely allergic to that we haven't yet tested for.
I'm searching for other ideas as to a cause or things we should suspect.