Red Dye 3 Vs Red Dye 40: What's The Difference?

In case you missed it, Red Dye No. 3 was banned in the United States on January 15, 2025, by the U.S. Food and Drug Administration. Food dyes like Red No. 3, also known by its chemical name erythrosine, are used by the food industry, much as you would expect, to brighten the hue of food products like candy, ice cream, and cereal, and some of them are still allowed under U.S. law, including Red No. 40. So what's different about Red No. 3?

The key lies in the Delaney Clause, a part of the Federal Food, Drug, and Cosmetic Act added in 1958 that prohibits the authorization of food additives that have been found to cause cancer in humans or animals. Although there haven't yet been any studies showing that this chemically developed substance causes cancer in humans, several studies published in the 1980s found during animal testing that the risk to male rats of developing cancerous thyroid tumors increased when given Red No. 3. The additive was banned in cosmetics in 1990 based on the same concerns, but a ban related to its use in food didn't pass until more than 30 years later — partly because the FDA says the specific effects of the dye in male rats have not appeared in similar studies done on humans and other animals.

Regardless, the food dye was (and is) controversial — as is Red No. 40, also known as Allura Red. Although both are similar substances derived from petroleum, they have different chemical makeups, with Red No. 3 specifically containing iodine. Whether Red No. 40 will be banned as well in coming years remains to be seen, but in the meantime, manufacturers have until 2027 to remove Red No. 3 from food products — and it's very possible that in making the switch, companies will begin using Red. No. 40 to enhance the color of certain products instead.

Wondering if either of these dyes are in the food you're eating? There's a rather long laundry list of products that use one of these dyes, but it's really going to depend on the company making them. In general, candy corn, popsicles, jellybeans, brightly colored beverages, and lollipops are likely culprits, while some more surprising additions include certain vegetarian meats and protein shakes. In general, food that's catered toward kids is more likely to rely on bright food dyes, but if you want to check for the dyes in any specific product, you can simply check the ingredients label. Note that in dyed foods from Europe, Red No. 3 is labeled as E127, while Red No. 40 is labeled as E129.

Many food companies in the process of removing Red No. 3 from their products will likely replace it with the legally permissible Red No. 40, but in certain states and countries, the laws concerning food dyes are even stricter, so additives that are legal in the U.S. may be banned in Europe. For example, in late 2024, the California Food Safety Act was signed into law, officially banning Red No. 40 (and a number of other food dyes) from being used in California public school lunches. The concerns around both food dyes partially have to do with them potentially acting as carcinogens, but that's not the only reason they're controversial. Although they have different chemical compositions, both Red No. 3 and Red No. 40 have also been linked to hyperactivity in some children, according to a 2021 Office of Environmental Health Hazard Assessment — especially when consumed in large quantities like, say, a whole bag of delicious, bright red Swedish fish.