Is Red 3 as Bad as Red 40? A Comparison

October 17, 2025 •

3 min read

In early 2025, the U.S. Food and Drug Administration (FDA) banned Red Dye No. 3 in food due to its link to cancer in animal studies. This raised questions for many consumers about whether Red 3 is as bad as Red 40, another widely used synthetic red dye.

Quick Summary

Red 3 was banned by the FDA due to cancer links, while Red 40 remains approved despite associations with hyperactivity and other health issues.

Key Points

Regulatory Status: Red 3 is banned in U.S. food due to cancer links in animal studies; Red 40 is federally approved.
Carcinogenic Risk: Red 3 caused thyroid cancer in rats; Red 40 isn't classified as a carcinogen but may contain contaminants.
Behavioral Effects: Red 40 is more strongly linked to hyperactivity and ADHD symptoms in susceptible children.
Chemical Makeup: Red 3 has iodine affecting the thyroid; Red 40 is an azo dye without that specific thyroid risk.
Veganism: Both are synthetic, technically vegan, but Red 40's animal testing history leads some vegans to avoid it.
Natural Alternatives: Natural colorants from plants like beets and paprika are safer options and increasingly used.

Comparing the Chemical Differences: What Separates Red 3 and Red 40?

Both dyes are artificial, petroleum-based color additives with differing chemical structures and health concerns. Red 3, or erythrosine, contains iodine, linked to thyroid effects. This influenced the FDA's ban. Red 40, or Allura Red AC, is an azo dye without the same thyroid risks. The chemical differences explain their differing regulatory status.

The Reason for Red 3's Ban: Carcinogenic Concerns

Research linked high doses of Red 3 to thyroid cancer in male lab rats. This evidence led the FDA to act under the Delaney Clause, which requires banning food additives found to cause cancer in animals. The ban on Red 3 became effective in early 2025, distinguishing it from Red 40.

The Controversies Surrounding Red 40

Red 40 is not conclusively classified as a carcinogen, though studies note carcinogenic contaminants like benzidine. Red 40 is primarily controversial for its association with behavioral problems in children, such as hyperactivity. Multiple studies connect synthetic dyes, including Red 40, to adverse neurobehavioral effects in susceptible children.

Research also suggests Red 40 might affect gut health and cause inflammation. A 2023 study in Nature Communications showed Allura Red AC caused gut inflammation in mice. While more research is needed, these findings raise concerns about regular Red 40 consumption.

A Comparative Look at Red 3 and Red 40


Feature	Red 3 (Erythrosine)	Red 40 (Allura Red AC)
Regulatory Status (USA)	Banned in food and ingested drugs as of 2025 due to carcinogenicity in rats.	Approved, but some states are restricting its use in school foods.
Main Health Concern	Link to thyroid cancer in male rats based on the Delaney Clause.	Linked to hyperactivity/ADHD in children; contains carcinogenic contaminants; potential gut inflammation.
Chemical Composition	Contains iodine, which affects thyroid function.	Azo dye, does not specifically target the thyroid.
Animal Testing	Found to cause thyroid tumors in high-dose rat studies.	Associated with increased tumor growth and DNA damage in some studies.
Behavioral Effects	Associated with hyperactivity, but evidence is less extensive than for Red 40.	Stronger evidence linking it to hyperactivity in susceptible children.
Vegan Status	Vegan (synthetic).	Vegan (synthetic), but often tested on animals.

The Takeaway for Consumers

The key difference is Red 3's proven status as a carcinogen in animals, leading to its ban. Red 40, though approved, is linked to hyperactivity in children and potential gut issues. Food advocacy groups advise avoiding all synthetic dyes due to risks and lack of nutritional value. Many manufacturers now use natural color alternatives like those from beets or paprika.

Natural Alternatives to Artificial Red Dyes

Natural colorants offer alternatives as manufacturers move away from Red 3 and consumers scrutinize Red 40. These provide color without synthetic dye concerns.

Beetroot Juice: Used for red/pink hues in various foods.
Paprika Extract: Provides reddish-orange.
Lycopene: A red pigment from tomatoes.
Anthocyanins: From fruits like cranberries, giving red/blue/purple.
Carmine/Cochineal Extract: A deep red dye from cochineal insects. It's natural but not vegan and can be an allergen, requiring labeling.

The Path Forward for Food Safety

The Red 3 ban is a significant U.S. food safety step, but highlights ongoing issues with dyes like Red 40. Consumer and advocacy pressure drives calls for stricter standards. In Europe, natural colorants are used to avoid hyperactivity warnings, showing reformulation is possible. Checking labels for "FD&C Red No. 40" or "Allura Red AC" helps minimize exposure. Informed consumers and manufacturers can increase demand for cleaner products.

Conclusion: Navigating the Red Dyes

Red 3 is arguably "worse" than Red 40 due to its FDA ban for links to animal cancer. However, Red 40 is not risk-free, with concerns about hyperactivity in children and potential contaminants. Given evolving understanding and consumer awareness, avoiding both dyes and opting for natural alternatives is often seen as the most prudent choice for health.

{Link: CSPI https://www.cspi.org/page/synthetic-food-dyes-health-risks-history-and-policy)}

Frequently Asked Questions

The FDA banned Red 3 because animal studies showed it caused thyroid cancer in male rats, aligning with the Delaney Clause.

No, Red 40 is still federally approved. Some states like California are restricting its use in school foods due to behavioral links.

Concerns include hyperactivity in sensitive children, allergic reactions, migraines, potential gut inflammation, and carcinogenic contaminants.

The FDA hasn't classified Red 40 as a carcinogen, but studies found carcinogenic contaminants. Evidence is less clear than for Red 3.

Natural options include beet juice, paprika extract, lycopene, and anthocyanins from fruits/vegetables.

Studies suggest dyes like Red 40 can exacerbate hyperactive/inattentive symptoms in susceptible children.

The FDA finds insufficient evidence for a total ban, deeming it safe at typical levels for most people. Red 3 was subject to the stricter Delaney Clause.