Blue 2

Additive

Blue 2 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 Blue No. 2.

Also known as

Blue 2

Why PRūF tracks it

PRūF tracks Blue 2 because research on synthetic food dyes has found changes in activity or attention in some children. The studies often test several dyes together, so those findings do not establish the effect of Blue 2 on its own, and results vary between studies and children. For parents and people limiting artificial colors, this is a concern worth knowing about; it is not evidence that Blue 2 causes ADHD or affects every child.

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 Blue 2. 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