FD&C Yellow No. 5, or tartrazine, is used to color beverages, desert powders, candy ice cream, custards and other foods. The color additive may cause hives in fewer than one out of 10,000 people. By law, whenever the color is added to foods or taken internally, it must be listed on the label. This allows the small portion of people who may be sensitive to FD&C Yellow No.5 to avoid it.
Source: Excerpted from FDA/IFIC brochure, January 1992: Food Additives