There Is a Difference Between Red Dye No. 3 and Red Dye 40 in Foods and Medicine

The US Food and Drug Administration (FDA) has banned the use of red dye no. 3 in foods in the United States. The ban is expected to take effect by January 2028, which is the date set for when manufacturers of foods and drugs that use the synthetic dye have to cease use of the coloring. But there is another dye found in foods and even medicine called red dye 40, so what’s the difference between red dye 3 and red dye 40?

Parents who have shared their experiences in online forums and otherwise about what they believe is behavior linked to red dye 40 have claimed that it’s the real culprit when it comes to unsafe coloring for foods. Red dye 3 has been found to cause cancer in lab rats, which is why the dye has been banned in the U.S. But many believe red 40 should have been first on the list.

Red dye 3 can be found in candy, drinks with unnatural coloring, puddings, and even bacon bits, depending on the brand. Red dye 40 can also be found in these items, though it is arguably more widespread. Even foods or candies that aren't red in color might still contain red dye 40 because of the way it mixes with other colors to achieve different shades.

Red dye 40 was found in studies to contain carcinogens, which can be linked to cancer. However, because the FDA has not properly studied or evaluated the safety risks of red dye 40 in foods and medicines in years, it is not banned in the U.S. While one is now banned and the other is still free to use by manufacturers in the U.S., there is a distinct difference in the shades of both red dyes. Red Dye 3 is brighter in color, while red dye 40 is a richer, darker red.

In some ways, this makes them easier to spot, depending on what snack food or candy you choose. But they are both believed to cause hyperactivity in children and even exacerbate anxiety in kids who consume foods with red dyes.

Some foods will have red dye 3 labeled right on the package, and the same goes for liquid medication that might be colored red or purple. But, according to Jamie Alan, RPh, PharmD, PhD, there is a sort of sneaky way that some nutrition or drug fact labels might list red dye 3.

"It's usually listed as red dye No. 3, but they could also technically put the name erythrosine," he told Contemporary Pediatrics. "And you want to look for other dyes as well. Red dye No. 40 has about four or five different names."

Brand name candies and foods with either red dye 3 or red dye 40 include Lifesavers, Ring Pops, Push Pops, and Brach’s. And pre-packaged icing, like Pillsbury’s Funfetti Valentine’s Day Vanilla Frosting, is one to take note of to avoid red dyes.

Even drinks can contain red dyes. Kool-Aid contains red dyes in some flavors. And outside of food, liquid medicine, whether it’s name brand or a store brand variety, might have red dye in it.