Red 40, Yellow 5, Yellow 6: What the Evidence Says

Red 40, Yellow 5, and Yellow 6 are the three most widely used synthetic food dyes in the US, and they've been the subject of debate for decades. This guide explains how they're regulated, what the research on children's behavior actually shows, where the rules are heading, and how to spot the dyes on an ingredients list.

What these dyes are

Synthetic food dyes are color additives made from petroleum-derived chemicals. The FDA calls them certified color additives, because each batch must be tested and certified by the FDA before it can be sold. The three most common are:

• FD&C Red No. 40 (Allura Red AC), used in candy, soft drinks, sports drinks, cereals, snack foods, and frostings.
• FD&C Yellow No. 5 (tartrazine), used in candy, soft drinks, chips, pickles, and boxed macaroni products.
• FD&C Yellow No. 6 (Sunset Yellow FCF), used in cereals, baked goods, candy, and orange-colored snacks and drinks.

These dyes add no nutrition or flavor. They're used to make food look brighter, more uniform, or more appealing, especially products marketed to children.

How the FDA regulates them

Color additives must be approved by the FDA before use, and approved uses are listed in federal regulations (Title 21 of the Code of Federal Regulations, Part 74, for certified colors). The FDA sets specifications for purity and requires batch certification.

On labels, certified color additives must be listed by name in the ingredients list, for example "Red 40" or "FD&C Yellow No. 5." Unlike some flavors, they can't be hidden under a general term like "artificial color." The FDA has noted that Yellow 5 can cause itching or hives in a small number of people, which is one reason it must always be declared.

What the research on behavior shows

The Southampton study

The most-cited study is a 2007 randomized trial from the University of Southampton in the UK, published in The Lancet. Researchers gave children drinks containing mixtures of synthetic dyes (including tartrazine and Sunset Yellow) plus the preservative sodium benzoate, or a placebo. On average, the dye mixtures were linked to small increases in hyperactive behavior in the general population of children, not only in children with ADHD.

The study had limits. It tested mixtures, so it couldn't say which dye, if any, was responsible. The effects were small and varied between children.

How regulators responded

Regulators reached different conclusions from similar evidence:

• European Union: Since 2010, foods containing six dyes, including Allura Red, tartrazine, and Sunset Yellow, must carry a warning that they "may have an adverse effect on activity and attention in children." The European Food Safety Authority (EFSA) re-evaluated these dyes and concluded the Southampton study alone wasn't enough to change the acceptable daily intakes, although it lowered the limits for some colors based on other data.
• FDA: In 2011, an FDA advisory committee reviewed the evidence and concluded that a causal link between certified dyes and hyperactivity in children in general had not been established, while acknowledging that some children with behavioral problems may be sensitive to them.
• California: In 2021, California's Office of Environmental Health Hazard Assessment (OEHHA) reviewed human and animal studies and concluded that synthetic food dyes can cause or worsen neurobehavioral problems in some children, and that federal safety levels may not be protective enough.

What we can say

The evidence suggests that some children may be sensitive to synthetic dyes, and that the effect on behavior, where it exists, is generally modest. The research does not show that dyes cause ADHD. Studies on cancer risk for Red 40, Yellow 5, and Yellow 6 at approved levels have not established a link, according to FDA and EFSA reviews. The picture is mixed, and scientists continue to study it.

Where the rules are heading

US policy on synthetic dyes has shifted recently. In January 2025, the FDA revoked the authorization for Red No. 3 (erythrosine) in food, citing the Delaney Clause because the dye caused cancer in male rats through a mechanism the FDA said is not relevant to humans. Food makers have until January 15, 2027 to remove Red No. 3 from food. On April 22, 2025, the FDA and HHS announced plans to phase out petroleum-based synthetic dyes, including Red 40, Yellow 5, and Yellow 6, from the US food supply, largely through voluntary industry commitments. The original goal was the end of 2026; the FDA's industry-pledge tracker now points to the end of 2027. As part of the same effort, the FDA has finalized revoking the authorization for Orange B and has proposed revoking Citrus Red No. 2. Several states, including California, have also passed laws limiting certain dyes, especially in school foods.

Many manufacturers have announced plans to switch to colors from natural sources, such as beet juice, paprika, turmeric, annatto, and spirulina extract. These colors are also regulated by the FDA, but they're exempt from batch certification. Because timelines vary by company and state, it's still worth checking ingredient lists.

Finding and avoiding dyes

Reading the ingredients list

• Look for the names. Red 40, Red 40 Lake, Yellow 5, Yellow 5 Lake, Yellow 6, Blue 1, and so on. "Lake" versions are the same dye bound to a mineral so it doesn't dissolve, used in coatings and candy shells.
• Don't rely on the color of the food. Dyes appear in foods you might not expect, like pickles, some yogurts, salad dressings, and brown-colored baked goods.
• Know the natural alternatives. Terms like "vegetable juice (color)," "beet juice concentrate," "paprika extract," or "annatto" mean the color comes from a natural source.

Should you avoid them?

Synthetic dyes provide no nutritional benefit, so there's no nutrition reason to seek them out. If your child seems sensitive, or you'd simply prefer to avoid them, cutting back is easy: the foods that contain the most dyes, such as candy, brightly colored cereals, and sports drinks, are also often high in added sugars. Parents concerned about a child's behavior should talk with a pediatrician rather than making broad diet changes alone.

How to use this on myfoodfact.com

myfoodfact.com shows the full ingredients list for every product, so dyes are easy to spot:

• Read about Red 40 and see products that contain it on our Red 40 ingredient page.
• Look up other colors and additives in the ingredient directory.
• Find products with long additive lists in products with the most additives.
• Learn how dyes fit into the bigger picture in our guide to ultra-processed foods.

The bottom line

Red 40, Yellow 5, and Yellow 6 are FDA-approved and must be listed by name on labels. Research suggests some children may be sensitive to them, but the effects are generally small and the evidence is mixed. US policy is moving toward phasing them out, and many brands are switching to natural colors. Reading the ingredients list is the most reliable way to know what's in your food today.

This guide is for general information and is not medical advice. If you think a food additive affects you or your child, talk with a doctor.