Red #40, also called Allura Red AC, is a synthetic food dye made from petroleum-based ingredients. It’s the most widely used artificial color additive in the United States, found in everything from candy and cereal to children’s cough syrup. The dye gives foods and drinks a bright red or orange-red appearance and has been at the center of ongoing debate about whether artificial colors affect children’s behavior.
What Red #40 Is Made From
Red #40 is a chemical compound with the formula C₁₈H₁₄N₂Na₂O₈S₂. It’s synthesized in a lab, not extracted from any natural source. The manufacturing process involves coupling two petroleum-derived chemicals together to form what’s called an azo dye, a class of colorants that get their vivid hues from nitrogen-to-nitrogen bonds in their molecular structure. The final product is a dark red powder that dissolves easily in water, which is why it works so well in liquids, frostings, and other processed foods.
Where You’ll Find It
Red #40 shows up in a surprising range of products, many of which don’t even look red. It’s blended with yellow dyes to create orange shades in chips and snack foods, and mixed into chocolate-colored frostings and puddings. The most common food categories include candy, gum, cereals, cakes and frosting, gelatin desserts, ice cream, popsicles, soda, sports drinks, energy drinks, yogurt, protein powders, and pastries.
It’s not limited to food. The FDA approves Red #40 for use in drugs and cosmetics as well. Many children’s medications, including liquid cough syrups and chewable tablets, contain it as an inactive ingredient. In cosmetics, it’s permitted for general use including products applied near the eyes, such as eyeshadow and eyeliner. Even toothpaste can contain it.
If you want to know whether a specific product contains it, check the ingredient label. It will be listed as “Red 40,” “FD&C Red No. 40,” or “Allura Red AC.”
How Your Body Processes It
Your body absorbs very little Red #40 intact. When the dye reaches your gut, bacteria break it apart at that nitrogen bond, splitting it into two smaller compounds. The vast majority of the dye and its breakdown products pass through your digestive system and leave in your stool. In animal studies, 76 to 95% of the dye was recovered in feces within 72 hours. Only a small fraction (roughly 3 to 20% depending on species) was excreted through urine, and almost none of that was the intact dye. The parent compound essentially doesn’t make it into your bloodstream in measurable amounts.
The Debate Over Children’s Behavior
The biggest concern around Red #40 involves hyperactivity in children. A 2007 study from Southampton University found that mixtures of artificial food dyes and the preservative sodium benzoate were linked to increased hyperactivity in children. That study prompted the European Union to require warning labels on foods containing Red #40 and five other dyes, stating the products “may have an adverse effect on activity and attention in children.”
A meta-analysis published in the Journal of the American Academy of Child and Adolescent Psychiatry looked across multiple studies and found a small but statistically significant effect. When children’s behavior was rated by parents, the effect size for food colors was 0.18, which is considered small. Teacher and observer reports showed a smaller, nonsignificant effect of 0.07. The most compelling finding came from psychometric tests measuring attention directly: those showed an effect size of 0.27, which held up even after adjusting for publication bias.
The researchers estimated that about 8% of children with ADHD may have symptoms related to synthetic food colors. That’s a meaningful subset, but it also means the vast majority of children, including most with ADHD, are unaffected. The effect appears to be strongest in children who already have attention difficulties, and it likely varies by individual sensitivity rather than being a universal reaction.
How the U.S. and Europe Differ
Red #40 is approved for use in the United States with no warning label required. The FDA has reviewed the evidence on behavioral effects multiple times and concluded that a causal link hasn’t been firmly established for the general population.
The European approach is more cautious. After reviewing the Southampton study, the European Food Safety Authority prompted the EU to require that foods containing Red #40 carry a warning about potential effects on children’s activity and attention. This hasn’t resulted in an outright ban, but many European food manufacturers have voluntarily reformulated their products with natural colorants to avoid the label.
In early 2025, the U.S. began moving closer to the European position. California became the first state to ban Red #40 and several other synthetic dyes from foods sold in schools, and federal legislation has been introduced to require broader labeling or restrictions.
Natural Alternatives
Several plant-based colorants can replace Red #40. Beet juice and beet powder produce reddish-pink tones. Red cabbage extract, hibiscus, and freeze-dried strawberry or raspberry powder also work. Carmine, a red pigment derived from cochineal insects, is another common substitute (though it’s not plant-based and not suitable for vegans).
These alternatives come with trade-offs. Natural colorings tend to be less vivid, fade faster in light and heat, and can add subtle flavors to food. Beet powder, for instance, carries an earthy taste that works in some products but not others. This is one reason manufacturers have been slow to switch: achieving the same bright, stable red that Red #40 provides is genuinely harder with natural ingredients, and it typically costs more.
Practical Takeaways for Avoiding It
If you’re trying to cut Red #40 from your family’s diet, the ingredient label is your only reliable tool. Color alone won’t tell you: some obviously red foods use natural colorants, while some brown, orange, or purple products contain Red #40 as part of a dye blend. Focus on the categories where it’s most common, particularly candy, flavored drinks, brightly colored cereals, and children’s medications. Many pharmacies now carry dye-free versions of common children’s medicines, though you may need to ask for them specifically.
Choosing whole or minimally processed foods eliminates the issue entirely, since Red #40 is only added to manufactured products. When buying packaged foods, look for products labeled “no artificial colors” or check for natural colorant names like “beet juice concentrate” or “vegetable juice for color” in the ingredients list.