Nitrates and nitrites are used to preserve foods, prevent deadly botulism infection, enhance flavors and color foods. They may rarely cause headaches and hives in some people. Nitrates and nitrites are used in hot dogs, bologna, salami and other processed meats and fish. They have been linked to chronic hives and other skin reactions on rare occasions. Benzoates are preservatives for some foods including cakes, cereals, salad dressings, candy, margarine, oils and dry yeast.
Benzoate reactions are very rare.
Today, scientists would demand stricter control of the process reported in 1959 to diagnose tartrazine as the cause of the hives. They question if other claims of adverse reactions to food additives are based on properly controlled studies showing a relationship. You may have reason to believe that you have adverse reactions to certain food additives. If you do, remove the additives from your diet for a few days. Your symptoms should promptly go away if the additive is the cause.