Allergy skin testing is highly reliable for food allergies related to milk, eggs, nuts, fish and other "whole" foods. However, there is no available allergy testing for food colors, preservatives, and artificial flavors.

In order to evaluate the possibility that your hives are related to a "hidden" food allergy, the only practical way is to proceed with an elimination diet. This involves not eating most "processed" foods including most deli items.

You will need to read labels so you can avoid eating foods that contain any artificial colors, artificial flavors, preservatives especially citric acid, BHA and BHT, and nitrates or nitrites often found in deli meats.

It is generally best to spend at least 1 day reviewing what you commonly eat at home to determine which foods will need to be "eliminated". Then spend another day shopping for foods that are "safe" to eat. While on the elimination diet you should not eat out. This diet should be strictly followed for a minimum of 5 days.

If after 5 days there has been no improvement in the hives, then a "hidden" food allergy is not the underlying cause. If your hives did dramatically improve, then there indeed may be a "hidden" food allergy. Now the fun really begins.