Red Dye 40 is made from petroleum. Specifically, it starts as crude oil, which undergoes a series of chemical reactions to produce a synthetic compound called Allura Red AC. It is not derived from any plant, animal, or mineral pigment. Every molecule of Red Dye 40 is built in a lab from petrochemical precursors.
From Crude Oil to Food Coloring
The production of Red Dye 40 begins with raw materials extracted from petroleum. Through a multi-step chemical synthesis, these petroleum derivatives are converted into an azo dye, a class of colorants defined by a specific nitrogen-to-nitrogen bond that gives the molecule its vivid red-orange hue. The final product dissolves freely in water, which is why it blends so easily into beverages, candy coatings, frostings, and sauces.
The finished dye is chemically stable. It doesn’t break down when exposed to light or air, and it holds its color across a range of acidity levels in food. That durability is a big part of why manufacturers favor it: a bag of candy or a bottle of sports drink looks the same on day one as it does months later on a store shelf.
Byproducts and Impurities
Because the synthesis starts with petroleum, the manufacturing process can generate unwanted byproducts. Red Dye 40 contains p-Cresidine, a compound considered a probable carcinogen. It also carries trace amounts of benzene, a known carcinogen. Benzene isn’t added intentionally; it forms as a side product during synthesis.
Federal regulations set limits on heavy metal contamination in each certified batch. Lead cannot exceed 10 parts per million, and arsenic cannot exceed 3 parts per million. Every batch of Red Dye 40 sold in the U.S. must be tested and certified to meet these purity standards before it can be used in food.
Where You’ll Find It
Red Dye 40 is the most widely used artificial food coloring in the United States. It shows up in candy, cereals, snack cakes, flavored chips, salad dressings, fruit-flavored drinks, and gelatin desserts. But food is only part of the picture. Medications and vitamins use it too, particularly cherry-flavored children’s cough syrups, where the red color reinforces the expected flavor. It also appears in cosmetics like lipstick, eyeliner, eyeshadow, and blush, as well as in soaps, bubble baths, and some children’s toothpastes.
Behavioral Effects in Children
The most active area of concern around Red Dye 40 involves children’s behavior. Meta-analyses of clinical challenge studies have found that synthetic food dyes are associated with inattentiveness, hyperactivity, and restlessness in children. These effects appear in kids with pre-existing behavioral disorders like ADHD and in children without any diagnosis.
Not every child reacts the same way. Research points to genetic differences that make some children more sensitive. Variations in genes involved in breaking down histamine and transporting dopamine appear to influence how strongly a child responds to synthetic dyes. In other words, two kids can eat the same red lollipop and have very different reactions based on their individual biology.
Several biological mechanisms have been proposed to explain how a food dye could affect behavior. Synthetic dyes may interfere with neurotransmitter systems, particularly dopamine and serotonin, by disrupting how nerve cells absorb or release these chemical messengers. Azo dyes like Red 40 may also trigger oxidative stress and inflammation in the brain, potentially driven by byproducts created when gut bacteria break down the dye. Some dyes can also prompt the release of histamine, a molecule involved in arousal and alertness, which could contribute to restless or hyperactive behavior in sensitive individuals.
Safety Limits and Regulatory Status
The European Food Safety Authority set an acceptable daily intake for Red 40 at 7 milligrams per kilogram of body weight per day. For a 45-pound child, that works out to roughly 140 milligrams, an amount that could realistically be reached in a day of eating brightly colored snacks, drinks, and candy.
In the U.S., the FDA and the Department of Health and Human Services announced plans to eliminate Red 40 and five other petroleum-based synthetic dyes from the nation’s food supply by the end of 2026. Until that phaseout takes effect, Red Dye 40 remains legal and widely used in American food products. The European Union already requires foods containing Red 40 to carry a warning label stating the dye “may have an adverse effect on activity and attention in children.”