A plain-English review of Erythrosine: what it is, why it appears on labels, safety context, common uses, and sources.
9/4/2026 · 7 min read · Chris Carrillo · Reviewed by Armin Rad, Co-Founder & CTO, Aurascan · Last reviewed 9/8/2026
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Written by Chris Carrillo. Reviewed by Armin Rad, Co-Founder & CTO, Aurascan. It cites 3 sources; use the source list and methodology to check the evidence directly.
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View the sample resultErythrosine (FD&C Red No. 3) is a synthetic cherry-pink organoiodine food dye. In January 2025, the FDA revoked its authorization for food and ingested drugs due to animal thyroid tumor findings under the Delaney Clause. Compliance deadlines require food reformulation by January 2027 and drug reformulation by January 2028.
Key takeaways:
Erythrosine is an organoiodine compound derived structurally from fluorone. Chemically known as the disodium salt of 2,4,5,7-tetraiodofluorescein, it carries the molecular formula C20H6I4Na2O5. According to the PubChem Compound Summary for erythrosine, it possesses a molecular weight of 879.86 g/mol and appears as a reddish-brown powder that dissolves readily in water to yield a brilliant watermelon-red hue.
The synthetic manufacturing process begins with petroleum distillates or coal tar derivatives. Phthalic anhydride reacts with resorcinol to synthesize fluorescein, which subsequently undergoes comprehensive iodination. Because four heavy iodine atoms bind directly to the aromatic xanthene core, iodine constitutes approximately 57.7% of erythrosine by total molecular mass. This distinct structural feature plays a central role in how the human gastrointestinal tract and endocrine system metabolize the compound.
Unlike azo colorants that produce bluish-red or orange-red hues, erythrosine provides a sharp neon pinkish-red shade. It demonstrates remarkable resistance to light degradation and heat, making it historically popular in processed foods requiring prolonged shelf stability.
Historically, erythrosine served as a primary coloring agent across confections, shelf-stable fruit preparations, cosmetics, and pharmaceuticals. For decades, it provided the bright pinkish-red tone in preserved maraschino cherries and canned fruit cocktail mixes because it binds tightly to plant cell walls without leaking into surrounding syrup.
In packaged groceries, consumers can still spot erythrosine across several categories:
Beyond food applications, erythrosine is utilized in oral medicines. Drug companies historically incorporated it into tablet coatings, gelatin capsules, and pediatric liquid syrups for dosage differentiation and brand recognition. In dental settings, clinical evaluations like the plaque disclosure randomized crossover trial on PubMed demonstrate its classic role as a plaque disclosing agent that temporarily stains bacterial biofilm pink to guide patient brushing.
Shoppers monitoring artificial ingredients across their pantry items can also read what is sucralose? uses, safety, baking risks, and labels or compare additive functions in is carrageenan safe? uses, safety, and regulatory status to evaluate current reformulation trends.
The regulatory history of FD&C Red No. 3 in the United States spans several decades. In 1990, the FDA prohibited erythrosine in cosmetics and externally applied drugs after laboratory bioassays revealed that high dietary intake induced thyroid follicular cell adenomas and carcinomas in male rats. Due to historical administrative divisions between provisional and permanent listing lists, however, its use in food and ingested pharmaceuticals remained legally permitted.
That legal standing changed definitively in January 2025. Following extensive citizen petitions and state-level legislation such as California's Food Safety Act, the research formally revoked authorization for Red No. 3 in foods and ingested drugs. The decision was mandated as a matter of law by the Delaney Clause of the Food Additives Amendment of 1958, which strictly prohibits the approval of any food additive shown to induce cancer in laboratory animals or humans, regardless of risk margins.
To ensure orderly supply chain adjustments and prevent nationwide drug shortages, the FDA established a phased transition. As of September 4, 2026, food manufacturers are finalizing reformulations ahead of the January 2027 food compliance deadline. Ingested pharmaceutical manufacturers producing prescription and over-the-counter medications have until January 2028 to achieve full compliance.
The scientific discussion surrounding erythrosine centers on endocrine disruption and pediatric behavioral responses. Because erythrosine carries four iodine atoms, substantial doses can alter the peripheral metabolism of thyroid hormones by inhibiting hepatic 5'-deiodinase enzymes. Animal toxicology reviews, including research on erythrosine-induced hepatic biomarkers and histopathological changes in male rats on PubMed, show that chronic exposure can increase thyroid-stimulating hormone (TSH) levels, stimulating continuous follicular cell growth.
Toxicological groups like the Joint FAO/WHO Expert Committee on Food Additives (JECFA) have noted that this rodent oncogenic mechanism relies on a sustained hormonal feedback loop that does not readily translate to human physiology at typical dietary exposures. Nevertheless, specific sensitive groups warrant consideration:
It is important to emphasize scientific uncertainty: current clinical evidence cannot establish whether low, intermittent dietary exposure causes direct long-term adverse health outcomes or carcinogenicity in healthy human adults. The majority of toxicological data stems from animal bioassays utilizing high daily concentrations.
Regulatory frameworks for erythrosine differ noticeably across global jurisdictions. In the European Union, the European Food Safety Authority (EFSA) established an Acceptable Daily Intake (ADI) of 0.1 mg per kg of body weight for erythrosine (E127). Decades ago, European regulators restricted authorized food uses almost exclusively to cocktail cherries and Bigarreaux cherries, capping concentrations at 150 mg to 200 mg per kg of product.
Consequently, conventional European foods such as baked goods, sodas, and candies avoid E127 entirely. Erythrosine belongs to the fluorone and xanthene chemical family rather than azo dyes; therefore, the mandatory EU warning label regarding activity and attention in children does not legally apply to E127. Nonetheless, retail demand has driven European manufacturers toward natural botanical colorants.
With the research 2025 revocation and enforceable 2027 and 2028 phaseout milestones, the United States is moving toward a strict stance that eliminates Red 3 from all conventional food items and ingestible drugs.
For readers following shifts across other certified colors, explore what is red 40? uses, safety, and pending studies regulations to compare safety profiles across distinct dye classes.
Until the mandatory compliance deadlines take full effect, erythrosine remains present on grocery shelves. Because ingredients must appear in descending order of predominance by weight, color additives typically occupy the bottom lines of the ingredient panel.
Look for these common label synonyms:
When reviewing pharmaceuticals, check the "Inactive Ingredients" panel on over-the-counter packaging or consult the pharmacist for prescription formulations.
Food and pharmaceutical manufacturers actively transitioning away from erythrosine utilize botanical pigments and certified synthetic alternatives. Replacing the fluorescent neon pink hue of Red 3 requires tailored formulations depending on product acidity and thermal processing.
Widely adopted alternatives include:
As manufacturers finalize their ingredient transitions ahead of the 2027 and 2028 deadlines, consumers will encounter an increasing variety of recognizable, plant-derived colorants across grocery aisles.
The FDA officially revoked authorization for FD&C Red No. 3 in food and ingested drugs in January 2025. However, the agency granted a compliance transition period: food manufacturers have until January 2027 to reformulate, while ingested drug makers have until January 2028.
Red 3 (erythrosine) is an organoiodine dye with a distinct bright cherry-pink tone that was banned by the FDA due to animal thyroid tumor studies. Red 40 (Allura Red AC) is an azo dye derived from petroleum that remains authorized for widespread food use, though it is subject to ongoing research regarding pediatric sensitivity.
In 1990, the FDA acted on cosmetics under the Delaney Clause based on male rat thyroid tumor data. However, due to procedural delays, separate regulatory petitions, and prolonged scientific debate regarding the relevance of the rat mechanism to humans, food authorization was not formally revoked until January 2025.
Erythrosine contains iodine and can alter thyroid hormone metabolism at high doses. In male rats, it causes thyroid tumors by stimulating excess thyroid-stimulating hormone. While human epidemiological evidence has not confirmed direct cancer risks at low dietary levels, the FDA banned it under statutory animal safety rules.
Until reformulation deadlines conclude in January 2027, Red 3 may still appear in maraschino cherries, seasonal candy canes, decorated baked goods, sprinkles, fruit snacks, cake decorating gels, and certain liquid pediatric medications.
E127 is the European additive number for erythrosine. In the European Union, its use is strictly limited to candied cherries, cocktail cherries, and specific pharmaceuticals, making it far less common on European grocery shelves.
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