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Health Education

Red 40 side effects and how to avoid them

Red Dye 40 is added to many foods and other products in the United States, but there have been growing concerns about its effect on ADHD and its carcinogenic ingredients
Racheal Ede
By | Dec. 1, 2023 Medically reviewed by Jesse P. Houghton, MD, FACG
A bottle of multicolored vitamins spilled over: Red 40 side effects and how to avoid them

Key takeaways

  • Red Dye 40 is a synthetic food additive derived from petroleum. In the United States, it’s used to enhance color in food products, drinks, cosmetics, vitamins, and medicines.

  • Red Dye 40 may impact ADHD symptoms in children and contains carcinogenic contaminants like benzidine. However, the FDA maintains it is safe for consumption.

  • Studies and clinical trials have suggested a link between Red Dye 40 consumption and increased hyperactivity in children, leading to recommendations for parents of susceptible children to avoid foods containing the dye.

  • Consumers should read nutrition labels carefully and opt for products that use natural food coloring instead of artificial dyes to avoid Red Dye 40 side effects.

In this article:

Red Dye 40 has been used for years as a popular synthetic food additive derived from petroleum and oils. Manufacturers add Red Dye 40 to products to make it more visually appealing to consumers and because it is more stable than natural food coloring. It is found in a variety of food products, drinks, cosmetics, vitamins, and over-the-counter medicines.

Red Dye 40 is among the most commonly used artificial food dyes in the United States, and you might see it labeled under a different name on the products you consume. Alternative names include Red 40, Red No. 40, Red 40 Lake, Allura Red AC, FD&C Red No. 40 Aluminum Lake, and FD&C Red No. 40. Regardless of what manufacturers label it as, there have been ties to specific negative side effects when ingested too frequently.

The controversy surrounding Red Dye 40

The U.S. Food and Drug Administration (FDA) certifies the Red Dye 40 as safe for human consumption. Apart from Red Dye 40, there are eight other certified color additives approved for use in food by the FDA: Blue No. 1, Blue No. 2, Green No. 3, Orange B, Red No.2, Red No.3, Yellow No.5, and Yellow No.6.

Despite being considered safe for consumption, there has been speculation about its safety among consumers—specifically in regard to attention-deficit hyperactivity disorder (ADHD) in children. The FDA has denied any link between the two for years. In 2011, the agency reported that it could not establish a relationship between color additives and hyperactivity in children in the general population. It did admit, however, that behavior among certain susceptible children with ADHD and other behavioral problems could be exacerbated by color additives such as Red 40. The FDA maintained this stance in 2019 after its Food Advisory Committee (FAC) reviewed the available evidence on color additives like Red 40 and their impact on children’s behavior. 

However, because certain studies suggest that some children may be more sensitive to color additives than others, the FDA recommended that parents check food labels for the ingredient list and avoid foods that contain additives that are triggering for their children. In Europe, foods containing artificial dyes such as Red 40, Yellow 5, and Yellow 6 come with a warning label that the dyes may adversely affect attention and activity in children.

Common side effects of Red 40 Dye

According to clinical research, Red 40 can cause hypersensitivity reactions—exaggerated or inappropriate immunologic responses to an antigen or allergen. While these reactions vary in nature, one commonly reported hypersensitivity reaction is ADHD. Cancer-causing carcinogens like benzidine have also been identified as contaminants in Red Dye 40.

Red Dye 40 and ADHD

ADHD is a neurodevelopmental disorder that often begins in childhood and may continue into adulthood. Symptoms include attention difficulty, hyperactivity, and impulsiveness. It was in 1973 that Dr. Benjamin Feingold presented a hypothesis at the annual meeting of the American Medical Association suggesting that hyperactivity in children could be linked to the consumption of artificial food coloring, according to an article published in the journal Neurotherapeutics. But his suggestions were dismissed. Feingold also observed that symptoms of hyperactivity improved when those color additives were removed from his patients’ diets. A clinical trial published in The American Journal of Psychiatry supports those findings. 

However, artificial food colors like Red Dye 40 aren’t the primary causes of ADHD, according to the journal Neurotherapeutics, though they may trigger some of its symptoms. This was seen in the , which consisted of 297 patients ages 3–9 who were classified across different ranges of hyperactivity. When the children ingested drinks containing a combination of various color additives (including Red Dye 40, also known as Allura red AC), they experienced a significant increase in hyperactivity.

A comprehensive 2021 report by California’s Office of Environmental Health Hazard Assessment (OEHHA) found a relationship between the consumption of synthetic food dyes, such as Red Dye 40, and adverse behavior problems in children with and without an existing behavior disorder.

Red Dye 40 and cancer

One of the ingredients found in Red Dye 40, benzidine, is a carcinogen. Studies suggest that long-term exposure to benzidine may increase the risk of bladder cancer. Benzidine was initially used to produce azodyes in the leather, textile, and paper industries. It is not currently produced in the United States, but it may be imported from other countries.

At the moment, there’s no conclusive evidence on the relationship between Red Dye 40 and cancer, and the FDA maintains that it has not approved any color additive found to cause cancer in animals or humans. 

Other Red Dye 40 side effects

Cleveland Clinic shares other potential side effects of Red Dye 40 that include:

  • Behavioral changes, such as irritability
  • Allergic reactions, such as hives and itching 
  • Sneezing
  • Watery eyes
  • Migraine

More research is needed to determine whether it is Red 40 that causes the above side effects since dyes are often used with other additives that could cause similar symptoms.

How soon do Red 40 side effects start?

According to anecdotal evidence from the Center for Science in the Public Interest, the side effects of Red 40 may be noticed within 10-20 minutes after ingestion.

How long do Red 40 side effects last?

The side effects of Red 40 may take 25 minutes, a few hours, or even a day to wear off completely, according to the CSPI. Some parents report improvement in their child’s behavior and other side effects when they remove foods containing Red Dye 40 from their children’s diet.

What are the long-term side effects of Red Dye 40?

There are no studies on the long-term side effects of Red Dye 40. The OEHHA, in its report, called for further research on “potential long-term effects of repeated brief exposures of food additives like the Red Dye 40 on brain development and function.”

Foods with Red Dye 40

Some of the most common foods that contain the Red Dye 40 include the following:

  • Breakfast cereal
  • Sports drinks
  • Soda and other soft drinks
  • Candy
  • Ice cream
  • Puddings
  • Popsicles
  • Gelatins
  • Cakes
  • Flavored yogurt and milk products

How to avoid Red Dye 40

Reading nutrition labels to scan for Red Dye 40 and any of its alternate names is the best way to avoid it. Cleveland Clinic recommends choosing products that use natural food coloring instead of artificial food coloring. Natural sources include beet juice and powder, blueberry juice, pomegranate juice, cranberries, cherries, strawberries, dried hibiscus flowers, and beta-carotene. 

Bottom line: Is Red 40 dye safe?

The FDA maintains that Red Dye 40 is safe for humans as long as it follows good manufacturing practices in accordance with its regulations. Moreover, it reiterates that all color additives undergo rigorous testing to ensure they meet composition and purity standards before approval for use. The FDA also assures consumers that it will continue following up on emerging scientific literature to ensure the color additive is safe. However, individuals may choose to remove food products containing the red food dye from their diet if they or their child is sensitive to it, if they are looking to limit processed foods, or if they have health concerns.