What is Erythrosine?


picture of maraschino cherries
Photo credit:WindyWinters

Erythrosine is an artificial red (cherry-pink) food colouring made from coal tar.  It is an organic compound containing iodine and sodium.  Erythrosine is also commonly referred to as red dye #3.

You might also hear erythrosine referred to as a xanthene dye.  Xanthene dyes are a group of brilliant fluorescent dyes ranging in colour from yellow to pink to bluish red.  They are called xanthene dyes because they all contain a xanthene molecule as their base.  To see what this means, lets look at a xanthene molecule.  The chemical formula for xanthene is C13H100, meaning there are 13 carbon atoms, 10 hydrogen atoms, and one oxygen atom. These atoms are arranged as shown:

picture of a xanthene molecule
Xanthene is the base molecule for Erythrosine

Now, what does Erythrosine look like?  The chemical formula for Erythrosine is C20H8I4O5. The following diagram shows the structure of the Erythrosine molecule. Can you see why it is called an xanthene dye?

picture of erythrosine
Erythrosine is used as a red food colouring

Common Uses:

Erythrosine is primarily used as a food dye. Some of the more common applications include:

  • cocktail and candied cherries (Maraschino cherries)
  • candies
  • popsicles
  • cake decorating gels
  • used to colour pistachio shells

Erythrosine is not used frequently in the US because Allura red is used instead. In 2008, the Center for Science in the Public Interest petitioned the FDA for a complete ban on erythrosine but so far, no action as been taken. It can still be used in the US without restriction.

Health Issues / Side Effects:

There have been concerns that the iodine may affect thyroid.  Some studies indicated a higher risk of thyroid tumors in rats.1

E Number:

The E number for erythrosine is 127.
Other common red food colours include Allura Red (E number 129) and Amaranth (E number 123).


According to the World Health Organization, erythrosine intake in Canada was 10 times higher than in either the US or Japan.2 In all cases, the intake was below established acceptable daily intake amounts. Still, given the possible health risks, I’d like to be able to see what products contain erythrosine. Unfortunately, in Canada, companies only need to list “colour” in their ingredients.


  1. European Food Safety Authority – Scientific Opinion on the re-evaluation of Erythrosine as a food additive

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8 Comments on “Erythrosine

  1. That was enlightening. At least it’s not made from cochineal beetles like Red #4 (Carmine). You got me curious about what’s in maraschino cherries so I looked it up. Gray & Company produces most of the retail maraschino cherries sold in the US and uses a different red dye, #40, which hasn’t had so many health concerns expressed about it. The bleaching process that all maraschino cherries go through seems pretty unappetizing, so even if they do use a safer dye, I’m not interested in eating them.

    • Thanks for the comment Mary.
      The red dye #40 you see in the ingredient list is also called Allura Red. Apparently, it is a common substitute in the US.
      I think that there are a lot of foods that people would find unappetizing if they only know how they were made.

  2. Is ERYTHROSINE the coloring for dental disclosing tablets given at the dentist’s office? How can I determine if the concentration warrents concern? My kids enjoy cocktail cherries.

    • I think in general you’d need to look at the ingredients on any product to see it contains erythrosine. However, based on a quick internet search it doesn’t look like it is used in dental disclosing tablets. For example, the active ingredient in Colgate tables is D&C Red28. This is not the same thing as erythrosine.

  3. Do you think that erythrosine will have adverse effect on plants for example in the case of iodine biofortification.
    I have been looking for an organoiodine compound for that.

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