Red 4 is a synthetic petroleum-derived red azo dye. Other names for Red 4 include CI 14700, FD&C Red No. 4, and Scarlet GN. It was once used as a food dye, however, it is no longer permitted for use in food or ingested drugs in the United States. Red 4 may only be used in externally applied drugs and cosmetics. In cosmetics and personal care products, Red 4 is used as a color additive. Color additives are classified as straight colors, lakes, and mixtures. Red 4 is a straight color, which means it has not been mixed or chemically reacted with any other substance. Red 4 can be found in makeup, nail polish, skin care, and many other products.