Artificial additives
Blue 2 (indigo carmine)
Definition
What it is
Artificial synthetic dye: linked to hyperactivity in children; requires mandatory warning label in the EU. The FDA is currently reviewing authorization following California's 2023 ban of several dyes in school foods.
On the label
How it appears on labels
- blue 2
- blue no. 2
- indigo carmine
- e132
Regulation
Regulatory status
- European Union Warning label required
- Japan Restricted
- United States Restricted
Explainer
In plain language
Blue 2, also known as indigo carmine or E132, is a synthetic dye used to give foods and drinks a deep blue color. It is made from petroleum-derived raw materials and does one job in food: appearance. It also has non-food uses, including as a diagnostic dye in medicine.
Assessment
Why it is flagged
Blue 2 was part of the group of synthetic dyes examined in the debate over color additives and children's behavior, though it was not among the specific dyes tested in the 2007 Southampton trial published in The Lancet. In the EU, foods containing certain synthetic colors must carry the warning 'may have an adverse effect on activity and attention in children', and EFSA has reviewed the additive and set an acceptable daily intake. In the United States the FDA continues to authorize Blue 2, but attention to synthetic dyes increased after California passed a 2023 law restricting several dyes in foods served in public schools. The behavioral evidence involves group-level associations and mixtures of dyes, and individual sensitivity varies, so Clear Label flags Blue 2 for transparency rather than declaring it harmful to everyone. Whether it tracks with anything you notice is the kind of pattern you can test in your own logs.
In the aisle
Where it commonly shows up
- Blue and purple candy and gummies
- Blue sports drinks and sodas
- Frozen ices and popsicles
- Frosting and cake decorations
- Some pet foods
- Some chewable medications and supplements
Practical
Reading the label
US labels list it as Blue 2, Blue No. 2, FD&C Blue No. 2, or indigo carmine. In the EU it appears as E132. It is sometimes combined with yellow dyes to produce green shades, so it can appear in products that are not visibly blue.
Alternatives
If you want to avoid it
Some people choose products colored with spirulina extract or other plant-based blues, or uncolored versions of the same snack. Comparing two labels side by side often reveals a dye-free option from the same brand.
FAQ
Common questions
Is Blue 2 banned anywhere?
As of 2026 Blue 2 is not broadly banned, but it is regulated. The EU permits it as E132 while requiring a child-activity warning on many products that contain synthetic colors, and the US continues to authorize it.
Is indigo carmine the same as Blue 2?
Yes. Indigo carmine is the chemical name for the same dye that US labels call Blue 2 and EU labels call E132.
Why did California's 2023 law matter?
California passed a law restricting several synthetic dyes in foods served in public schools, which increased regulatory attention on the category. That kind of state-level action can prompt broader reviews, though it does not itself ban a dye nationwide.
Citations
Sources
Citation
Primary reference
About this page: the definition, label names, severity, and regulatory chips come from the clearlabel ingredient taxonomy, the same data the scanner uses to score products. Research summaries describe associations reported in published studies, not diagnoses; individual responses vary. Scan any product with clearlabel to see which of its ingredients carry flags.