What Red 40 is
Red 40 (also called Allura Red AC, or E129 in Europe) is a synthetic dye derived from petroleum. It produces a bright red to orange-red color and is one of the most commonly used artificial colorants in the food supply.
Despite the name, it doesn't always make food look red. Depending on the formulation, it can produce orange, pink, or purple tones. Many products listed as "cherry," "strawberry," or "fruit punch" flavored get their color partly or entirely from Red 40.
It's water-soluble, stable under acidic conditions, and inexpensive, which is why it shows up so widely. Unlike natural colorants (beet juice, annatto), synthetic dyes like Red 40 don't fade with heat or light exposure, making them reliable for processed food manufacturing.
Where it shows up
Red 40 is in a wider range of products than most people expect:
- Fruit-flavored cereals and cereal bars
- Sports and energy drinks
- Gummies, hard candies, and fruit snacks
- Gelatin desserts and pudding mixes
- Strawberry and cherry flavored yogurt
- Some fruit juices and juice drinks
- Certain flavored chips and snack crackers
- Maraschino cherries
- Some medications and vitamins (particularly children's formulations)
It shows up on labels as "Red 40," "Red 40 Lake," or "FD&C Red No. 40." The "Lake" version is an oil-dispersible form used in products where you need color in a fat-based medium.
The hyperactivity debate
The most significant ongoing controversy around Red 40 involves behavior in children. In 2007, a study published in The Lancet found that a mixture of food colorings (including Red 40, along with five other dyes) plus sodium benzoate (a common preservative) was associated with increased hyperactivity in children.
The UK's Food Standards Agency reviewed this research and concluded the evidence was strong enough to recommend that manufacturers voluntarily remove the six colorings studied. The European Union went further: products containing any of these six dyes must now carry a label warning that the product "may have an adverse effect on activity and attention in children."
The EU warning label reads: "may have an adverse effect on activity and attention in children." This is a required statement for any food in the EU containing Red 40, not just a voluntary caution.
The FDA reviewed the same research and concluded it did not establish a causal link between the dyes and hyperactivity in the general population. They noted that a subset of children with ADHD may be sensitive to these dyes, but declined to require labeling or remove the dyes from the approved list.
Several US states and the FDA itself have periodically reconsidered this position. As of 2026, Red 40 remains on the FDA's approved list with no required warning label in the United States or Canada.
The sensitivity question
Even if Red 40 doesn't affect most children in a measurable way, the evidence suggests some individuals (particularly those already diagnosed with ADHD) may be more reactive to synthetic dyes as a group.
This is where the research gets complicated. It's difficult to run a clean controlled trial on children's behavior. Parental perception of hyperactivity is subjective. And the original Lancet study tested a combination of dyes plus a preservative. It wasn't a clean test of Red 40 alone.
What the research doesn't show is a strong, consistent, population-level effect in healthy children with no pre-existing attention difficulties. What it does suggest is that some children may benefit from reducing synthetic dye intake. The evidence for a population-wide ban is weaker than the EU's decision implies; the evidence for some sensitivity in a subset of children is stronger than the FDA's inaction implies.
Other safety concerns
Beyond hyperactivity, some researchers have raised questions about potential carcinogenicity and genotoxicity based on animal studies. These concerns have been reviewed by regulatory agencies, and the current scientific consensus at the FDA and EFSA is that Red 40 is not carcinogenic at typical intake levels.
What EFSA's review concluded: Red 40 (E129) is acceptable for use in food and does not raise carcinogenicity concerns based on available data. The hyperactivity question is treated separately from the broader safety profile.
Red 40 may also cause allergic reactions in people who are sensitive to aspirin or salicylates, though this is uncommon. If you've noticed a pattern of reactions to brightly colored foods and you're aspirin-sensitive, it's worth noting.
Why the regulatory gap exists
The US and Europe have taken meaningfully different positions on Red 40. This isn't unique: the same gap exists for several other additives and is a consistent feature of how the two regulatory systems approach uncertainty.
The EU's approach tends toward precaution: when evidence of potential harm exists, even if inconclusive, require disclosure or restrict use. The FDA's approach requires a higher bar of demonstrated harm before action.
Neither position is obviously wrong. They reflect different values around how much risk society is willing to accept without clear evidence of harm, and who bears the burden of proof: the manufacturer or the regulator.
How to check what's in your food
Red 40 is easy to find on a label once you know what to look for. It's always listed by name ("Red 40" or "Red 40 Lake"), so there's no hidden alias issue. The problem is that most people don't read labels carefully enough to catch it, especially in products where you don't expect artificial color (some "natural" sounding products contain it).
NoJunk reads ingredient labels with your camera and flags every additive worth knowing about. No barcode needed. Just point at the label.
The bottom line
Red 40 is not definitively proven to be harmful to most people at typical intake levels. That's an honest reading of the current evidence.
What's also true: the EU has decided the potential effect on children's behavior is sufficient to require a warning label. That's a reasonable position given the Lancet research. And if you have a child with ADHD or attention difficulties, the evidence is strong enough that removing synthetic dyes is worth trying, even if it's not proven to help in every case.
The goal isn't to make you anxious about everything on the label. It's to make sure you can see what's actually there.