What are the health concerns of erythrosine?

November 15, 2025 •

3 min read

In early 2025, the U.S. Food and Drug Administration (FDA) banned the use of Red Dye No. 3, also known as erythrosine, in food and ingested drugs due to its health concerns. This decision was based on decades of research highlighting potential risks associated with the additive, particularly concerning thyroid health and carcinogenicity.

Quick Summary

This article examines the health risks associated with erythrosine (Red Dye #3), including its potential to cause thyroid dysfunction, trigger tumors in animal studies, and contribute to behavioral issues like hyperactivity, as well as recent regulatory changes.

Key Points

Thyroid Disruption: Erythrosine is known to interfere with thyroid hormone regulation by inhibiting the conversion of T4 to T3, which can lead to elevated TSH levels.
Carcinogenic Potential: High-dose animal studies linked erythrosine to benign thyroid tumors in rats, forming the legal basis for regulatory action in the U.S. under the Delaney Clause.
Neurobehavioral Effects: The dye has been controversially linked to hyperactivity and other behavioral issues in children, a concern highlighted by the 2007 Southampton study.
Recent Bans: The U.S. FDA officially banned the use of erythrosine (Red Dye No. 3) in food and ingested drugs in January 2025.
Limited Human Relevance: Many regulatory agencies have historically deemed the carcinogenic risks observed in rodents to be of limited relevance to humans due to metabolic differences, though recent bans have prioritized a more cautious approach.
Poor Absorption: Erythrosine is poorly absorbed by the human body and largely eliminated in the feces, which limits systemic exposure but does not eliminate all potential health concerns.

Introduction to Erythrosine (Red Dye #3)

Erythrosine, or FD&C Red No. 3 (E127), is a synthetic food dye historically used to give a bright cherry-red color to a wide range of products, including candies, frostings, maraschino cherries, and certain medications. Its petroleum-based origins and potential health risks have made it a subject of extensive research and regulatory action over several decades. While once widespread, its use has become increasingly restricted in many countries due to mounting evidence of its negative effects, prompting a major shift in food production and consumer awareness.

Thyroid Health Concerns

One of the most significant health concerns regarding erythrosine is its effect on thyroid function. Being an iodine-containing compound, erythrosine can interfere with the body's thyroid hormone metabolism, leading to a cascade of hormonal imbalances. Studies indicate that erythrosine acts as a 5′-deiodinase inhibitor, blocking the enzyme responsible for converting T4 into T3. This can lead to elevated TSH levels, which may overstimulate the thyroid gland.

Comparison of Erythrosine's Thyroid Effects in Rats vs. Humans


Feature	Rats (Animal Studies)	Humans (Short-Term Studies)
Dose Levels	Carcinogenic effects observed at extremely high doses, far exceeding typical human exposure.	Minimal effects noted in short-term studies, requiring doses significantly higher than the Acceptable Daily Intake (ADI).
TSH Levels	Elevated TSH levels due to impaired peripheral T4-to-T3 conversion.	Dose-related increases in serum iodide and TSH at very high intake, though TSH levels often remained within the normal range.
Thyroid Tumors	Linked to benign thyroid tumors (adenomas and carcinomas) at very high chronic exposure, believed to be secondary to hormonal effects.	No evidence links typical consumption levels to thyroid cancer, based on established differences in thyroid physiology compared to rodents.
Overall Risk	The carcinogenic effects in rats were a primary driver for the FDA ban, particularly under the strict Delaney Clause.	Regulatory bodies like EFSA and FSANZ have historically concluded minimal human risk at normal exposure levels due to species-specific metabolic differences.

Carcinogenic Concerns and Regulatory Action

Animal studies linking high doses of erythrosine to benign thyroid tumors in rats provided the basis for the FDA's decision to ban the dye from food and ingested drugs in 2025 under the Delaney Clause. The FDA had previously banned the dye for cosmetics in 1990 due to similar concerns. Pressure from advocacy groups and state actions, like California's 2023 ban, preceded the federal ban. The official ban on its use in food and ingested drugs in the US took effect in January 2025.

Neurobehavioral Issues in Children

A potential link between erythrosine and behavioral issues like hyperactivity in children has been explored. A UK study connected a mix including erythrosine to adverse behavioral effects in children. While some research suggests interference with neurotransmitters, other reviews find evidence linking typical consumption levels to behavioral changes inconsistent.

Other Health Considerations

Other potential health impacts have been investigated.

Allergic Reactions and Hypersensitivity: Some individuals may experience hypersensitivity or allergic reactions to erythrosine.
Oxidative Stress: Rat studies indicate erythrosine may increase oxidative stress and trigger neuroinflammation in the brain.
Poor Absorption and Metabolism: Erythrosine is poorly absorbed by the body and is largely eliminated unchanged, limiting systemic exposure but not all risks.

Conclusion

What are the health concerns of erythrosine? The evidence points to risks, primarily its disruptive effect on thyroid function and carcinogenic potential at high doses in animal studies. This led to its eventual ban from food and ingested drugs in the U.S. in 2025 under the Delaney Clause. Potential links to behavioral issues and allergic reactions are also concerns. The recent ban highlights the importance of ongoing research and evaluation of synthetic food additives. {Link: PBS https://www.pbs.org/newshour/health/the-fda-banned-red-3-food-coloring-a-scientist-explains-the-dyes-history-and-health-risks}

Frequently Asked Questions

Erythrosine, also known as FD&C Red No. 3 or E127, is a synthetic, petroleum-based food and drug dye used to give products a cherry-red color.

The U.S. FDA banned erythrosine in food and ingested drugs based on a long-standing law called the Delaney Clause, which requires banning any food additive that causes cancer in animals. Decades of animal studies demonstrated that high doses of the dye caused thyroid tumors in rats.

Some studies, like the 2007 Southampton study, have suggested a link between erythrosine and other artificial dyes with hyperactivity, especially in sensitive children. While regulatory bodies and research are still debating the evidence for typical consumption levels, it remains a serious concern for many parents and consumers.

Erythrosine disrupts thyroid function by inhibiting the conversion of T4 to T3, a key metabolic process, and can lead to increased TSH levels at higher doses. This was a central concern in its regulatory assessment.

While the FDA's ban was legally mandated by animal study results, the cancer risk to humans at typical low consumption levels has been debated. Agencies like EFSA and FSANZ have historically concluded that the specific hormonal mechanism causing tumors in rats is likely not relevant to humans due to physiological differences.

Before the 2025 ban in the U.S., erythrosine was found in many products, including candies, fruit-flavored snacks, icings, maraschino cherries, and certain medications and cough syrups.

Many food manufacturers now use natural coloring alternatives to achieve a red hue. These include beet juice, carmine (a dye from insects), or pigments derived from sources like purple sweet potato, radish, and red cabbage.