Red Dye 40 shows up in candy, cereal, sports drinks, yogurt, fruit snacks, and even children’s cough syrup. It is the most widely used red food dye in the United States, added to thousands of products purely for color. It has zero nutritional value.

In Europe, every product containing Red Dye 40 must carry a health warning. In America, no such label exists. Same ingredient. Same research. Different rules.

Here is what the science actually says, what regulators decided, and what is changing right now.

What is Red Dye 40?

Red Dye 40, also called Allura Red AC (labeled as E129 in Europe), is a synthetic food coloring derived from petroleum. It belongs to a class of chemicals called azo dyes. The FDA classifies it as a certified color additive, meaning each manufactured batch must pass chemical testing before use in food.

You will find Red Dye 40 in breakfast cereals, candy, fruit snacks, sports drinks and sodas, flavored yogurts, and children’s liquid medications. In fact, it exists in these products for one reason: to make them look more appealing. It does nothing for taste, texture, or nutrition.

Is Red Dye 40 banned in Europe?

No. Red Dye 40 is not banned in Europe. The dye, known in the EU as Allura Red AC or E129, remains legal under European food additive regulations.

However, since July 2010 the European Union has required a warning label on foods containing six synthetic dyes, including Red Dye 40. Under EU Regulation 1333/2008, products containing these colorings must display the statement:

“May have an adverse effect on activity and attention in children.”

This labeling rule followed the 2007 Southampton Study, which suggested a possible link between mixtures of artificial food dyes and increased hyperactive behavior in some children.

The label requirement created a strong incentive for manufacturers to reformulate their products rather than print a warning on the package. As a result, many European versions of cereals, candies, and drinks removed Red Dye 40 entirely and switched to natural colorings.

So while Red Dye 40 is still technically legal in Europe, the mandatory warning label dramatically reduced its use across the European food supply.

The study that changed everything

The controversy traces back to a landmark clinical trial published in The Lancet in 2007, widely known as the Southampton Study. Specifically, researchers at the University of Southampton tested 153 three-year-olds and 144 eight- and nine-year-olds in a randomized, double-blinded, placebo-controlled trial.

Children who drank juice containing mixtures of artificial food dyes (including Red Dye 40) combined with the preservative sodium benzoate showed small but measurable increases in hyperactive behavior compared to those who drank the placebo. The reported Red 40 side effects were behavioral, not allergic or toxic, and appeared most clearly in children who were already sensitive to additives.

Two important caveats. First, the study tested dye mixtures, not Red Dye 40 in isolation. Second, the researchers described the link as “possible,” not proven. They acknowledged that many factors contribute to hyperactivity and that removing dyes alone would not necessarily prevent behavioral disorders.

Still, the findings were significant enough to trigger regulatory action on one side of the Atlantic.

What happened in Europe

In response to the Southampton Study and a growing body of evidence, the European Union acted. Under EU Regulation 1333/2008, which took effect in July 2010, any food product containing one of six synthetic dyes, including Red Dye 40, must display a mandatory warning:

“May have an adverse effect on activity and attention in children.”

Europe did not ban Red Dye 40. It remains legal throughout the continent. But the warning label created a powerful market incentive. Rather than print a health warning on their packaging, most manufacturers simply reformulated their products to remove the synthetic dyes.

As a result, Red Dye 40 largely disappeared from European shelves, not because of a ban, but because of a label.

What happened in America

In March 2011, the FDA convened a Food Advisory Committee to review the same body of research. The 14-member panel of doctors, food scientists, and consumer representatives voted 8 to 6 against recommending warning labels for artificial food dyes. In their view, the evidence did not establish a causal relationship between food dyes and hyperactivity in the general child population. A 2012 review in the journal Neurotherapeutics later noted that while the overall effect sizes were small, the data did support a link in susceptible subgroups.

The vote was close, nearly half the panel wanted action. However, the majority held, and no federal labeling requirement followed.

The California review that added pressure

In 2021, California’s Office of Environmental Health Hazard Assessment (OEHHA) released a comprehensive review of synthetic food dyes and child behavior. The assessment examined 27 clinical trials and concluded that synthetic food dyes can cause or worsen neurobehavioral problems in some children.

Furthermore, the OEHHA report found that the FDA’s acceptable daily intake levels for synthetic dyes relied on studies conducted between the 1960s and 1980s, none of which tested for behavioral effects. The peer-reviewed publication of the findings reinforced the conclusion that current federal guidelines may not adequately protect children.

States are not waiting for the FDA

California became the first state to target food dyes. In September 2024, Governor Newsom signed the California School Food Safety Act, banning Red Dye 40 and five other synthetic dyes from public school food starting December 31, 2027.

In March 2025, West Virginia went further. Governor Morrisey signed HB 2354 into law, banning seven synthetic food dyes from school meals (effective August 2025) and from all food sold in the state by January 2028. It became the first state with a comprehensive food dye ban beyond schools. However, a federal judge temporarily blocked the statewide provisions in December 2025 while legal challenges play out, though the school meal ban remains in effect.

The momentum is bipartisan and accelerating. During 2025 alone, 38 states introduced over 140 food additive bills, and eight states enacted school food dye restrictions into law.

Meanwhile, at the federal level, the FDA announced in April 2025 that it had reached voluntary agreements with food manufacturers to phase out six petroleum-based dyes, including Red Dye 40. But this is not a ban. The Center for Science in the Public Interest noted that the FDA issued no rulemaking of any kind, the entire plan rests on an industry “understanding,” not enforceable law.

How Red Dye 40 rules compare: EU vs US vs states

European UnionUnited States (federal)US states
StatusLegal with mandatory warning labelLegal, no warning requiredBanned in school food in 8+ states
Rule typeEnforceable regulation (EU 1333/2008)Voluntary industry “understanding”Enforceable state law
Effective sinceJuly 2010April 2025 (voluntary phase-out)August 2025 (WV schools) to December 2027 (CA schools)
ResultMost products reformulated to avoid labelStill in thousands of productsCompliance ongoing, legal challenges active

Watch our full breakdown

We turned this entire regulatory story into a 60-second animated short. Two food characters walk through the science, the 8-6 FDA vote, and why “understanding” is not the same as a ban. If you want to share one thing about synthetic food coloring with someone who does not read food policy articles, this is it.

What you can do right now

No study has proven that Red Dye 40 causes hyperactivity in all children. But multiple independent reviews have found that some children appear sensitive to synthetic food dyes, and the effects on attention and behavior are real for that subset.

If your child struggles with attention, focus, or behavioral issues, reducing artificial dye exposure is a low-risk step worth trying. In other words, flip the package over and read the ingredient list.

Look for any of these names:

  • Red 40
  • Allura Red AC
  • FD&C Red No. 40
  • E129

If you see them, you can choose an alternative. Many brands already offer versions without synthetic dyes, especially those sold in Europe where the warning label made reformulation the easier path.

This same habit of checking ingredient lists applies across your entire diet. We covered a similar label-reading issue with juice marketing in our article Is Orange Juice Healthy?.

The bottom line

Europe requires a warning label on Red Dye 40 because of possible behavioral effects in children. The United States does not. That gap is closing, 38 states introduced food dye bills in 2025 alone, but federal rules still rely on voluntary industry cooperation.

Europe did not ban Red Dye 40. Europe labeled it. That label was enough to make most of it disappear from European food. In America, the ingredient remains in thousands of products, and the only person checking the label is you.

We break down one misleading food label every week. If you want to know what is really in your food before you buy it, subscribe to What in the Food and we will send it straight to your inbox.

Frequently asked questions

Is Red Dye 40 banned in Europe?

No. Red Dye 40 (Allura Red AC, E129) is legal throughout the European Union. However, since July 2010, any food product containing it must carry a warning label stating it "may have an adverse effect on activity and attention in children." Most manufacturers removed the dye voluntarily to avoid printing the warning.

Does Red Dye 40 cause ADHD?

Research has not established that Red Dye 40 causes ADHD. The 2007 Southampton Study found a possible link between mixtures of artificial food dyes and increased hyperactive behavior in some children, but the effect was small and the study tested dye combinations, not Red 40 alone. Multiple reviews confirm that some children appear sensitive to synthetic food colorings, but sensitivity is not the same as causation of a clinical disorder.

Which foods contain Red Dye 40?

You will find Red Dye 40 in candy, breakfast cereals, sports drinks, sodas, flavored yogurts, fruit snacks, and children’s liquid medications such as cough syrup. It is the most widely used red food dye in the United States. Check the ingredient list for "Red 40," "Allura Red AC," "FD&C Red No. 40," or "E129."

Is Red 40 being phased out in the US?

Partially. In April 2025, the FDA announced voluntary agreements with food manufacturers to remove six petroleum-based dyes, including Red 40. However, this is not a ban or enforceable regulation. At the state level, eight states enacted school food dye restrictions in 2025, and West Virginia passed the first comprehensive statewide ban, though a federal court has temporarily blocked its broader provisions.

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