Red 40 (Allura Red AC, E129) is the most widely used artificial food dye in the United States, found in thousands of products from candy to cereal to sports drinks. Here's what the research says about its effects.

What Is Red 40?

Red 40 is a petroleum-derived synthetic food dye that produces a bright red color. It's listed on ingredient labels as "Red 40," "Allura Red AC," "FD&C Red No. 40," or "E129" (European designation).

Known Side Effects

Hyperactivity in Children

The most well-documented effect of Red 40 is increased hyperactivity in children. The landmark 2007 Southampton Study published in The Lancet found that mixtures of food dyes (including Red 40) combined with sodium benzoate increased hyperactivity in both 3-year-olds and 8-9 year olds.

Allergic Reactions

Some individuals experience allergic-type reactions including hives, itching, and swelling. These reactions are more common in people who are also sensitive to aspirin.

Potential Carcinogenicity

While Red 40 itself hasn't been classified as a carcinogen, some studies have found it can contain low levels of carcinogenic contaminants from the manufacturing process, including benzidine and 4-aminobiphenyl.

Important: The FDA is phasing out Red 40 along with other synthetic dyes by the end of 2027. Read more about the FDA food dye ban.

Common Products Containing Red 40

Want to skip both the dyes AND the seed oils? Many of the snacks and chips that contain Red 40 also contain canola or soybean oil. Make chips at home without seed oils or dyes using Origin Recipe.

Use DyeFreeCheck to scan any product and see if it contains Red 40 or other artificial dyes. Browse dye-free candy and dye-free snacks for alternatives.