The red colorings most widely flagged as harmful are Red Dye No. 3 (erythrosine) and Red Dye No. 40 (allura red), both synthetic food additives used across thousands of processed foods in the United States. Red 3 is being banned outright due to a legal clause tied to cancer findings in animals. Red 40, the most consumed red dye in the country, is linked to behavioral effects in children and gut inflammation in animal studies, and the FDA announced plans to phase it out by the end of 2026.
Red Dye No. 3: Banned Under Cancer Law
Red 3 caused thyroid tumors in male rats exposed to high levels of it, triggering a legal requirement that forced the FDA’s hand. The Delaney Clause, part of federal food law since 1960, prohibits any color additive shown to cause cancer in humans or animals, with no exceptions for dose or likelihood. The FDA itself has stated that the mechanism behind those rat tumors does not occur in humans, and studies in other animals and people did not show the same effects. Still, the law is absolute: Red 3 must go.
In January 2025, the FDA formally revoked authorization for Red 3 in food and drinks, giving manufacturers until 2027 to reformulate. Medications containing it have until 2028. California had already moved first, passing the California Food Safety Act in October 2023, which banned Red 3 along with three other additives. That state law also gives manufacturers until 2027 to comply.
You’ll find Red 3 listed on labels as FD&C Red No. 3 or erythrosine. It has historically appeared in candy, cake decorations, maraschino cherries, and certain medications.
Red Dye No. 40: Behavioral and Gut Health Concerns
Red 40 is far more widely used than Red 3 and has drawn a different set of concerns. The best-studied issue is its effect on children’s behavior. A major set of clinical trials tested mixtures of artificial food colors (including Red 40) against a placebo in both preschoolers and 8- to 9-year-olds. Parent ratings showed small but statistically significant increases in hyperactivity when children consumed the color mixes, with effect sizes in the range of 0.12 to 0.2. That’s a modest effect at the population level, but for sensitive children, it can be more pronounced.
Genetic differences help explain why some children react more than others. Variations in genes involved in histamine processing and dopamine transport significantly influenced how strongly kids responded to the dye mixtures. The dyes may trigger a direct release of histamine from immune cells and may cause the body to waste zinc through excessive excretion, both of which can affect brain function without the dye itself ever reaching the brain.
Animal research has raised a separate concern: gut health. A 2023 study in mice found that Red 40 damaged DNA both in lab dishes and in living animals. When mice consumed Red 40 alongside a high-fat diet for 10 months, they developed low-grade inflammation in the colon and significant disruptions to their gut bacteria. Beneficial bacterial communities decreased while harmful ones increased. Gut bacteria break Red 40 down into metabolites that themselves appear to have inflammatory and DNA-damaging properties. These findings align with other research showing Red 40 can trigger colitis in animal models. The relevance to humans at typical dietary levels is still being studied, but the pattern is concerning enough that the FDA announced in April 2025 it would phase out Red 40 and several other synthetic dyes by the end of 2026.
Where Red 40 Hides in Your Diet
Red 40 shows up in a surprisingly wide range of products, many of which don’t even look red. Common sources include candy, gum, cereals, chips, energy drinks, gelatin desserts, ice cream, pastries, popsicles, protein powders, pudding, soda, sports drinks, and yogurt. On ingredient labels, it may be listed as Red 40, Red 40 Lake, FD&C Red No. 40, or FD&C Red No. 40 Aluminum Lake.
Children’s medications are another overlooked source. Liquid cough syrups and chewable tablets frequently contain food dyes, including Red 40, to make them more visually appealing.
How Europe Handles These Dyes Differently
The European Union hasn’t banned Red 40 (called allura red, or E129, in Europe), but it takes a stricter approach than the U.S. has historically taken. Any food or drink containing Red 40 or five other artificial colors must carry a mandatory warning label stating: “May have an adverse effect on activity and attention in children.” That labeling requirement has effectively pushed most European food manufacturers to switch to natural colorings, since the warning discourages consumers from buying the product. The practical result is that the same brand-name snacks and cereals sold in Europe often use plant-based colors while their American versions use synthetic dyes.
Carmine: A Natural Red With Its Own Risk
Not all concerning red colorings are synthetic. Carmine (also called cochineal extract, Natural Red 4, or E120) is a natural red dye made from the dried bodies of female cochineal insects. It’s widely used in cosmetics, yogurt, juice, and candy. For most people it’s harmless, but it can trigger allergic reactions ranging from hives and facial swelling to full anaphylactic shock.
Over 80 cases of carmine hypersensitivity have been formally documented worldwide, with the majority reported in Japan. In one clinical study, researchers challenged 33 patients who had chronic hives with oral doses of carmine. Eight tested positive for an allergic reaction. Symptoms ranged from generalized hives and itching to one patient who developed massive hives with difficulty breathing just 20 minutes after a moderate dose. Because the first allergic reaction to carmine can be severe, people with chronic hives or known sensitivity to insect-derived products should check labels carefully.
Plant-Based Red Alternatives
The most common natural replacements for synthetic red dyes come from beets, elderberries, red cabbage, hibiscus, and prickly pear (Opuntia) fruit. These carry no behavioral or carcinogenic concerns, but they come with practical tradeoffs that explain why manufacturers have been slow to adopt them.
Heat stability is the biggest challenge. Beet-based pigments are extremely sensitive to temperature: in lab testing, beet extract retained only about 12.5% of its color after sustained heating, and prickly pear extract kept less than 2%. Anthocyanin-based extracts from elderberry and red cabbage held up better, retaining roughly 64% and 46% of their color respectively, but still degraded significantly compared to synthetic dyes that barely change. Hibiscus fell in between at about 27%. This means products that undergo baking, pasteurization, or long shelf storage often lose their color when using plant-based alternatives. As reformulation deadlines approach, manufacturers are working to solve these stability problems, and you can expect to see more products listing beet juice, fruit and vegetable extracts, or anthocyanins on their ingredient panels in the coming years.