My 3 year old daughter gets hives from potassium sorbate (preservative 202). The first reaction came from home made pizza. I made the base from scratch but used a jar pizza sauce. The reaction was quite dramatic and scary. She came up in bright red hives all around her mouth within minutes. They lasted approximately 1 1/2 hours. I raced her down to the GP (I have another child with severe food allergies so I was terrified it was happening again). I also had no idea what ingredient in the pizza had caused the reaction. Obviously pizza contains some high risk foods as far as allergies go (dairy, wheat) but she'd eaten every ingredient in the past except the pizza sauce. We were referred to a paediatric allergist. He didn't know what ingredient caused the reaction and felt it was unnecessary to put such a young child through further testing.

After 2 weeks we tried the pizza sauce again and she reacted again. We were told it wasn't a serious reaction and to avoid that brand of pizza sauce. A couple of months later she reacted to a new brand of margarine and the only ingredient they have in common is preservative 202. One other thing, she didn't have any other obvious allergy symptoms (vomiting etc) and, at the time, she didn't complain about the inside of her mouth but I also wonder if it gave her an unpleasant sensation inside her mouth. Months later, she still refuses to eat pizza and margarine/butter. It's pretty unusual for a 3 year old to request vegemite on toast with no margarine or butter. Prior to the reaction she happily ate sandwiches and toast with margarine. - Vicki, by email