Is Yellow 5 as Bad as Red 40? Comparing the Health Concerns of Common Food Dyes

October 11, 2025 •

4 min read

The consumption of artificial food dyes has increased dramatically over the past several decades, with Red 40, Yellow 5, and Yellow 6 being the most common ones found in U.S. foods. While both Yellow 5 and Red 40 are widely used, concerns over their safety—particularly in children—raise questions about how their potential health risks compare.

Quick Summary

Despite widespread use, Yellow 5 and Red 40 are subjects of ongoing debate regarding health risks. Yellow 5 is most linked to allergic reactions, while Red 40 has stronger associations with gut inflammation and potential DNA damage, though both dyes face concerns over behavioral effects in sensitive children.

Key Points

Allergy vs. Inflammation: Yellow 5 is more strongly linked to allergic reactions and hypersensitivity, while Red 40 shows more evidence connecting it to gut inflammation and altered gut microbiome composition.
Behavioral Concerns: Both Yellow 5 and Red 40 are associated with hyperactivity and attention issues in sensitive children, a link that has been acknowledged by regulatory bodies like the FDA and OEHHA.
Cancer-Causing Contaminants: Both dyes may contain low, regulated levels of benzidine and other carcinogenic contaminants, though studies on their long-term effects on human cancer risk are limited.
Regulatory Differences: The European Union requires warning labels for foods containing these dyes, while the US FDA recently announced plans to phase them out, reflecting differing regulatory stances.
Natural Alternatives: Many food manufacturers are moving towards natural colorants derived from sources like fruits and vegetables, offering a dye-free choice for concerned consumers.
Avoidance Strategy: For those concerned, the most effective approach is to limit consumption of processed foods, which are the primary source of these synthetic dyes.

Artificial food dyes are pervasive in the modern diet, added to thousands of products to make them visually appealing. However, as consumers become more health-conscious, the safety of these petroleum-derived chemicals has come under intense scrutiny. The most popular of these are FD&C Red No. 40 (Allura Red) and FD&C Yellow No. 5 (Tartrazine), and while both are approved by the U.S. Food and Drug Administration (FDA), their potential health effects and regulatory histories differ, influencing public perception and regulatory action.

Yellow 5: A History of Hypersensitivity Concerns

Yellow 5, also known as tartrazine, has long been associated with allergic-type reactions.

Allergic Reactions and Sensitivities

Studies indicate that Yellow 5 can trigger hypersensitivity reactions in a small portion of the population, often manifesting as hives, skin rashes, or asthma symptoms. Individuals with aspirin sensitivity or asthma appear to be at a higher risk. Rare cases of swelling (angioedema) have also been linked to this dye.

Behavioral Effects in Children

Yellow 5 has been implicated in behavioral issues, including hyperactivity, in some children. Reports, like the 2021 one from California's OEHHA, suggest a link between synthetic food dyes, including Yellow 5, and adverse neurobehavioral effects in certain children. Earlier studies, such as the UK-based Southampton study, also found a connection between a mixture of dyes, including Yellow 5, and increased hyperactivity.

Potential for Genotoxicity and Carcinogenic Contaminants

While Yellow 5 is not considered a direct carcinogen, concerns exist regarding low levels of carcinogenic contaminants like benzidine that may be present. Some in vitro and animal studies suggest tartrazine can induce oxidative stress and damage DNA, raising questions about potential long-term risks, especially with high intake.

Red 40: Inflammation, DNA Damage, and the Hyperactivity Debate

Red 40, or Allura Red AC, is the most widely used food dye in the United States and is associated with health concerns.

Gut Health and Inflammation

Recent animal studies highlight Red 40's potential impact on digestive health. A 2023 study in mice indicated that continuous exposure to Red 40 harms gut health and causes inflammation by altering the gut microbiome and increasing serotonin production. This chronic inflammation is a concern due to its potential link to long-term issues, including colorectal cancer.

DNA Damage and Carcinogenic Contaminants

Similar to Yellow 5, Red 40 may contain trace amounts of known carcinogens, such as benzidine. A 2023 study found that Red 40 caused DNA damage in lab cell cultures and animals, leading researchers to describe it as a "dangerous compound".

Hyperactivity and Behavioral Effects

The link between Red 40 and hyperactivity is supported by studies and reports like those from the California OEHHA. While not everyone is sensitive, regulatory agencies acknowledge that some susceptible children may experience exacerbated behavioral issues from consuming food dyes.

Comparing Yellow 5 and Red 40


Feature	Yellow 5 (Tartrazine)	Red 40 (Allura Red AC)
Primary Allergic Concern	Higher, particularly in aspirin-sensitive individuals.	Present, but less commonly cited as a primary allergy concern.
Hyperactivity Link	Supported by studies, especially in sensitive children.	Strong evidence linking it to hyperactivity in sensitive children.
Carcinogenic Contaminants	Contains benzidine and other potential carcinogens at low, regulated levels.	Contains benzidine and other potential carcinogens at low, regulated levels.
Specific Long-Term Animal Studies	Some studies suggest genotoxicity and oxidative stress.	Recent studies show links to gut inflammation, microbiome changes, and DNA damage.
EU Regulation	Requires a warning label: "May have an adverse effect on activity and attention in children.".	Requires a warning label: "May have an adverse effect on activity and attention in children.".
US Regulatory Status	FDA approved, but a recent FDA statement in 2025 indicated action to phase out Yellow 5 and other dyes.	FDA approved, but plans were announced in April 2025 to phase out Red 40.

Making Informed Choices About Artificial Dyes

The FDA has historically considered certified color additives safe at approved levels, but ongoing research and differing global regulations present a more complex picture. The European Union mandates warning labels on foods with these dyes, and in 2025, U.S. health officials announced intentions to phase out eight petroleum-based dyes, including Yellow 5 and Red 40.

For those concerned about potential health effects, prioritizing whole, unprocessed foods is key, as this naturally reduces exposure to artificial additives. When buying processed foods, checking ingredient lists for names like Allura Red AC or Tartrazine is important. Many manufacturers now use natural alternatives such as beet juice, paprika, or turmeric.

Conclusion: Navigating the Food Dye Debate

Neither Yellow 5 nor Red 40 is definitively worse; each is primarily associated with different concerns based on scientific evidence. Yellow 5 is most linked to allergic reactions, while Red 40 has stronger evidence suggesting ties to gut inflammation and potential DNA damage. Both are significantly associated with hyperactivity in sensitive children. Both dyes are non-nutritive additives to processed foods. The growing scientific evidence is leading many to choose natural, whole-food alternatives, and is driving a global move toward phasing out these synthetic additives.

For more information on food dye regulation in the US, consult the FDA Website on Food Color Additives.

Frequently Asked Questions

Yellow 5 is most notably associated with allergic reactions, including hives and asthma symptoms, especially in individuals with aspirin sensitivity. Red 40 has more recent animal study evidence linking it to gut inflammation and potential DNA damage.

Yes, multiple studies have linked both Yellow 5 and Red 40 to behavioral issues like hyperactivity and inattentiveness in certain children. Some children may be more sensitive to these effects than others.

While neither dye is officially classified as a carcinogen, both have been found to contain low levels of carcinogenic contaminants like benzidine. However, the human health implications of these trace amounts are still under scientific investigation.

In 2010, the European Union began requiring warning labels on foods containing certain synthetic dyes, including Yellow 5 and Red 40, to state that they "may have an adverse effect on activity and attention in children". This decision was based on research like the Southampton study. The FDA has previously concluded that the evidence for causality was not strong enough for a similar warning, but is now planning a phase-out.

Natural alternatives used by food manufacturers include beet juice for reds, turmeric for yellows, and paprika for oranges. Choosing whole foods that are naturally colorful, like fruits and vegetables, is another effective strategy.

While there is no conclusive evidence that these dyes are dangerous for all people, the evidence linking them to behavioral issues in sensitive children and other potential health effects is strong enough for many people to choose to avoid them. Those with specific sensitivities, such as aspirin sensitivity, may benefit from avoidance.

Yellow 5 and Red 40 are common in a wide range of processed foods and beverages, including candy, cereals, sports drinks, gelatins, baked goods, and condiments. It is important to read the ingredient list to identify these additives, which can be listed by their full name, number, or E-number.