Ingredient review

Blue 1 Lake

INCI: CI 42090

A widely used synthetic blue dye that is generally safe in cosmetics but offers no skincare benefits.

beautyskincarecolorant

In plain English

CI 42090, also known as Blue 1 Lake or FD&C Blue No. 1, is a man-made blue pigment. It's added to cosmetics and personal care products to give them a blue color. Think of it like food coloring for your makeup. It doesn't do anything for your skin—it's purely there for looks. It's been used for decades and is considered safe in the tiny amounts found in cosmetics.

Quick decision guide

Useful, but context matters

Blue 1 Lake is generally a lower-concern ingredient when the full formula suits your skin.

Plain-English read

Treat this as a practical screening step before you compare products that contain this ingredient.

  1. Step 1Start with the score, then check the irritation and clogging risk before judging Blue 1 Lake.
  2. Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
  3. Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.

Score terms in plain English

Irritation risk

low

Less likely to sting, burn, or bother most users, though sensitive skin can still react.

Clogging risk

low

Less likely to feel heavy or contribute to clogged pores for most skin types.

Evidence level

strong

There is a stronger practical or research basis for the ingredient role described here.

What it is

CI 42090 is a synthetic organic compound derived from petroleum. It's a triarylmethane dye that is processed into a lake (insoluble pigment) by combining it with aluminum hydroxide. This lake form is stable and doesn't bleed or dissolve in water, making it ideal for use in powders, creams, and lip products.

How it works

In a cosmetic product, CI 42090 works by absorbing and reflecting specific wavelengths of light, which our eyes perceive as blue. As a pigment, it sits on the surface of the skin or nail and provides color without being absorbed. It does not interact with the skin's biology.

Pros

Vibrant and stable color

Provides a bright, consistent blue hue that doesn't fade or change easily in the product over time.

Low irritation potential

At the low concentrations used in cosmetics, it rarely causes skin irritation for the general population.

Cons and cautions

No skin benefit

This ingredient is purely cosmetic. It does not hydrate, protect, or improve the skin in any way.

Synthetic origin

Derived from petroleum, which may be a turn-off for consumers looking for natural or sustainable ingredients.

Best for

  • Anyone who wants blue-colored cosmetics
  • People with normal skin not prone to allergies from synthetic dyes

Use caution if

  • Individuals with known allergies to FD&C dyes
  • Those seeking only natural or plant-based ingredients

Usage tips

Check the ingredient list if you have a known sensitivity to FD&C dyes.
Patch test a new colored product on your inner arm before applying to your face.
Store products containing lakes in a cool, dry place to maintain color stability.

Safety summary

CI 42090 is considered safe for use in cosmetics at regulated concentrations. Rare allergic reactions have been reported. It does not penetrate the skin and poses no known health risks when used as intended.

Research notes

Extensive safety evaluations by the FDA and EU SCCS have confirmed its safety in cosmetics. Studies focus on oral ingestion (food) rather than topical use, but dermal absorption is negligible.

Common label clues

Typical concentration
Very low, typically less than 1%
Regulatory status
Approved as a color additive for cosmetics in the US (FDA) and EU (EC). Subject to purity and usage restrictions.
Common uses
Eyeshadows, Lipsticks, Nail polishes, Hair dyes, Soaps, Bath products
Environmental note
As a synthetic petroleum-derived dye, it is not biodegradable and may accumulate in water systems. Proper disposal is recommended.

Good to know

  • CI 42090 is the same dye used in many blue foods and beverages.
  • The 'Lake' form means it's insoluble and won't stain the skin as easily as the water-soluble version.
  • It is approved for use in cosmetics in the US, EU, and many other countries.

Common questions

What is Blue 1 Lake in beauty products?

CI 42090, also known as Blue 1 Lake or FD&C Blue No. 1, is a man-made blue pigment. It's added to cosmetics and personal care products to give them a blue color. Think of it like food coloring for your makeup. It doesn't do anything for your skin—it's purely there for looks. It's been used for decades and is considered safe in the tiny amounts found in cosmetics.

What does Blue 1 Lake do in a beauty product?

In a cosmetic product, CI 42090 works by absorbing and reflecting specific wavelengths of light, which our eyes perceive as blue. As a pigment, it sits on the surface of the skin or nail and provides color without being absorbed. It does not interact with the skin's biology.

Is Blue 1 Lake safe for most people?

CI 42090 is considered safe for use in cosmetics at regulated concentrations. Rare allergic reactions have been reported. It does not penetrate the skin and poses no known health risks when used as intended.

Who should be careful with Blue 1 Lake?

Individuals with known allergies to FD&C dyes Those seeking only natural or plant-based ingredients

Research sources

FDA Color Additive Status ListOpenCosmetic Ingredient Review (CIR) Safety AssessmentOpenPubChem - Brilliant Blue FCFOpen

Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.