There are thousands of additives used by the food industry for a variety of purposes in the foods we eat. However, only a small number have been implicated in causing adverse reactions in humans. Although there are reported cases of individuals who have reactions to single additives, most of the medical literature involves patients with asthma or chronic idiopathic urticaria/angioedema whose conditions are exacerbated after ingestion of food additives. Many of these reports are characterized by poorly controlled challenge procedures. Recent studies performed under properly controlled conditions imply that sensitivity to food additives in patients with chronic urticaria/angioedema is very uncommon.