Red 40

Additive

Red 40 is a manufactured coloring added to foods and drinks. It can be used on its own or mixed with other colors to create different shades. Ingredient labels may list it as FD&C Red No. 40.

Also known as

Red 40 · FD&C Red No. 40

Why PRūF tracks it

PRūF tracks Red 40 because research on synthetic food dyes raises concerns about changes in activity and attention in some children. Red 40 studies in mice have also found DNA damage and gut inflammation, although other animal tests found no DNA damage and the same effects have not been established in people. For parents and people who want to limit artificial dyes, these findings make Red 40 an ingredient worth checking before ordering.

This research covers a group of six dyes. Findings about one member do not establish the same effects for every dye.

Read the research

This page identifies Red 40. The following evidence describes the shared six-dye assessment, including findings that apply only to specified members. Synthetic dyes are a group, and findings for one dye do not establish equal effects from all others.

Controlled challenge studies support changes in activity or attention in some children, but results vary across doses, mixtures, observers and individuals. A review of 25 challenge studies found a behavioral signal in some trials; a later Hong Kong trial found no significant adverse effect. These studies do not show that dyes cause ADHD or that every child reacts. Laboratory studies also raise questions about particular dyes: Red 40 affected DNA and intestinal inflammation in mice, while other guideline tests were negative.

A 2026 study found that Sunset Yellow worsened experimentally induced egg-protein allergy in mice given 40 milligrams per kilogram of body weight; this is not evidence that ordinary food exposure causes human allergy. West Virginia restricts the six named dyes in school nutrition meals, and California has enacted school restrictions beginning December 31, 2027, with specified exceptions. Generic “artificial color” wording can include other pigments, so the named ingredient matters.

Research reviewed on September 5, 2026 · 12 sources