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Brilliant Blue FCF

Brilliant Blue FCF is a synthetic blue dye used in foods, medicines, dietary supplements, and cosmetics.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 27, 2026|2 min read| Fact-checked

Brilliant Blue FCF is a synthetic blue dye used in foods, medicines, dietary supplements, and cosmetics. It is also known as FD&C Blue No. 1, Acid Blue 9, and E133. The dye is a triarylmethane compound and is one of the long-established colour additives approved for use in food and ingested drugs.

Names and classification

Brilliant Blue FCF is a synthetic dye known by several names, including FD&C Blue No. 1, Acid Blue 9, and E133. It belongs to the triarylmethane dye family.

Chemical properties

The compound is commonly described as a blue or reddish-purple powder and is soluble in water and glycerol. Sources also note a maximum absorbance around 628 nanometres and a molecular formula of C37H34N2Na2O9S3.

Uses

The dye is used in processed foods, medications, dietary supplements, cosmetics, and some household products. It is also used in research and, in some contexts, as a tracer dye.

Regulation and safety

Brilliant Blue FCF has long been an approved colour additive in food and ingested drugs in the United States. JECFA evaluated toxicology data and set an acceptable daily intake of 0–6 mg/kg body weight per day.

Key facts

  • It is a synthetic organic colourant used to produce blue colouring in consumer products.
  • It is classified as a triarylmethane dye.
  • It is identified as E133 in the European food additive system and as FD&C Blue No. 1 in the United States.
  • Its chemical identity is described as a disodium salt with formula C37H34N2Na2O9S3.
  • Brilliant Blue FCF is approved by FDA for use in food and ingested drugs and was permanently listed in 1969.
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Canadian context

In Canada, Brilliant Blue FCF is relevant as a regulated food and cosmetic colour additive that may appear on ingredient labels under names such as E133 or FD&C Blue No. 1.

Frequently asked questions

What is Brilliant Blue FCF?
A synthetic blue dye used mainly as a colour additive in foods, medicines, supplements, and cosmetics.
What other names is it known by?
Common names include FD&C Blue No. 1, Blue 1, Acid Blue 9, and E133.
What type of chemical is it?
It is a triarylmethane dye, specifically used as a colourant.
What is its chemical formula?
Its molecular formula is C37H34N2Na2O9S3.
Is it approved for food use?
Yes. It is one of the older FDA-approved colour additives and has been permanently listed for use in food and ingested drugs since 1969.
What is its safety limit?
JECFA established an acceptable daily intake of 0–6 mg/kg body weight per day based on toxicology studies.

References

  1. Wikipedia — https://en.wikipedia.org/wiki/Brilliant_blue_FCF
    Supports: Common names, classification, E number, Colour Index, physical description, FDA food/drug listing date
  2. PubChem (NIH) — https://pubchem.ncbi.nlm.nih.gov/compound/FD_C-Blue-No.-1
    Supports: Chemical identity and description as a sodium salt
  3. International Association of Color Manufacturers — https://iacmcolor.org/color-profile/brilliant-blue-fcf-fdc-blue-no-1/
    Supports: CAS number, names, physical description, applications
  4. WHO JECFA — https://apps.who.int/food-additives-contaminants-jecfa-database/Home/Chemical/3309
    Supports: Synonyms, ADI, toxicology basis, food safety assessment
  5. FAO JECFA monograph — https://www.fao.org/fileadmin/user_upload/jecfa_additives/docs/Monograph1/additive-059-m1.pdf
    Supports: Chemical description and composition
  6. ScienceDirect Topics — https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/brilliant-blue-fcf
    Supports: Triarylmethane classification and food additive use