Ingredient review

Acid Yellow 1

INCI: CI 10316

A synthetic yellow dye that is generally safe in rinse-off cosmetics but offers no skincare benefit.

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In plain English

CI 10316 is a man-made yellow colorant used to give a bright yellow hue to products like soap, shampoo, and bath bombs. It does not improve your skin or hair—it's purely for appearance. In small amounts in products that you rinse off quickly, it is considered safe by regulators, but some people with very sensitive skin may prefer to avoid synthetic dyes.

Quick decision guide

Useful, but context matters

Acid Yellow 1 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 Acid Yellow 1.
  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

moderate

There is useful support, but formula details and claim strength still matter.

What it is

CI 10316 is a synthetic organic pigment classified as a nitro dye. It is also known as Acid Yellow 1 or Naphthol Yellow S and is approved for use in cosmetics in many regions, including the EU and the US (where it is listed as D&C Yellow No. 1 for external use only).

How it works

It works by absorbing and reflecting specific wavelengths of light, giving the product a yellow color. It does not interact with the skin or hair biologically—its role is purely aesthetic.

Pros

Vibrant color

Delivers a consistent, bright yellow shade that is stable in most rinse-off formulations.

Regulatory approval

Approved for use in cosmetics by major regulatory bodies like the FDA and EU Commission when used within limits.

Cons and cautions

No skin benefit

Provides zero skincare or haircare benefit—it is purely decorative.

Potential irritant

While generally safe, it can cause contact dermatitis or irritation in very sensitive individuals, especially in leave-on products.

Best for

  • Anyone using rinse-off products who does not have a known sensitivity to synthetic dyes
  • Consumers who prioritize product appearance and color consistency

Use caution if

  • Individuals with known allergies or sensitivities to synthetic colorants
  • Those seeking only natural or organic formulations

Usage tips

Use only in rinse-off products to minimize skin contact time.
Patch test if you have a history of reactions to synthetic dyes.
Check the full ingredient list—dyes are often listed near the end.

Safety summary

CI 10316 is considered safe for use in rinse-off cosmetics at typical concentrations. The Cosmetic Ingredient Review (CIR) panel has reviewed similar nitro dyes and found them safe when formulated to be non-irritating. However, it offers no functional benefit and may cause reactions in sensitive individuals.

Research notes

Limited peer-reviewed research specifically on CI 10316 in cosmetics. Safety assessments rely on general toxicology data for nitro dyes and regulatory reviews. No strong evidence links it to serious health risks at cosmetic use levels.

Common label clues

Typical concentration
Typically less than 1% in rinse-off products
Regulatory status
Approved for use in cosmetics in the US (external use only) and EU (Annex IV). Always check local regulations as restrictions vary.
Common uses
Soaps, Shampoos, Bath products, Hair dyes
Environmental note
Synthetic dyes can persist in water systems; proper disposal and wastewater treatment are important to minimize environmental impact.

Good to know

  • In the US, CI 10316 is listed as D&C Yellow No. 1 and is restricted to external use only.
  • In the EU, it is permitted in cosmetics under Annex IV with specific purity criteria.

Common questions

What is Acid Yellow 1 in beauty products?

CI 10316 is a man-made yellow colorant used to give a bright yellow hue to products like soap, shampoo, and bath bombs. It does not improve your skin or hair—it's purely for appearance. In small amounts in products that you rinse off quickly, it is considered safe by regulators, but some people with very sensitive skin may prefer to avoid synthetic dyes.

What does Acid Yellow 1 do in a beauty product?

It works by absorbing and reflecting specific wavelengths of light, giving the product a yellow color. It does not interact with the skin or hair biologically—its role is purely aesthetic.

Is Acid Yellow 1 safe for most people?

CI 10316 is considered safe for use in rinse-off cosmetics at typical concentrations. The Cosmetic Ingredient Review (CIR) panel has reviewed similar nitro dyes and found them safe when formulated to be non-irritating. However, it offers no functional benefit and may cause reactions in sensitive individuals.

Who should be careful with Acid Yellow 1?

Individuals with known allergies or sensitivities to synthetic colorants Those seeking only natural or organic formulations

Research sources

Cosmetic Ingredient Review (CIR) - Color AdditivesOpenFDA - Color Additives in CosmeticsOpenEU CosIng Database - CI 10316Open

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.