Ingredient review
HC Blue No. 16
INCI: HC Blue No. 16
A synthetic blue dye for hair color that is generally safe for most people but may cause allergic reactions in sensitive individuals.
In plain English
HC Blue No. 16 is a man-made blue colorant used in hair dyes to give hair a blue or cool-toned tint. It is not intended for skincare or makeup around the eyes. Like many hair dyes, it can occasionally cause skin irritation or allergic reactions, so a patch test is recommended before full use.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is useful, but some claims depend heavily on the formula.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
HC Blue No. 16 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.
- Step 1Start with the score, then check the irritation and clogging risk before judging HC Blue No. 16.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- 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
lowLess likely to sting, burn, or bother most users, though sensitive skin can still react.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
moderateThere is useful support, but formula details and claim strength still matter.
What it is
HC Blue No. 16 is a synthetic anthraquinone dye that imparts a blue color to hair. It is classified as a 'HC' (hair color) ingredient and is approved for use in cosmetic hair dyes in many regions, including the EU and the US.
How it works
In a hair dye product, HC Blue No. 16 deposits onto the hair shaft's outer cuticle, staining it blue. Because it does not penetrate deeply, the color is semi-permanent and gradually washes out over several shampoos.
Pros
Vibrant color payoff
Delivers a strong blue hue that can be used alone or mixed with other dyes for custom shades.
Fades gradually
Because it is semi-permanent, the color washes out over time, reducing the need for frequent root touch-ups.
Cons and cautions
Allergy risk
Like many synthetic hair dyes, it can cause allergic reactions, so a patch test is essential before use.
Staining potential
Can temporarily stain skin, towels, and clothing if not applied carefully.
Best for
- People looking for semi-permanent blue or cool-toned hair color
- Those who want to experiment with color without long-term commitment
Use caution if
- Individuals with known allergies to hair dyes or p-phenylenediamine (PPD)
- People with sensitive scalps or active skin conditions on the scalp
Usage tips
Safety summary
HC Blue No. 16 is considered safe for use in hair dyes at typical concentrations when used as directed. The main safety concern is the potential for allergic contact dermatitis, which can be minimized by performing a patch test before each use.
Research notes
Research on HC Blue No. 16 is limited, but it is part of a class of HC dyes that have been evaluated by the Cosmetic Ingredient Review (CIR) panel and found safe for use in hair dyes under current use practices. No significant systemic toxicity has been reported from topical application.
Common label clues
- Typical concentration
- Typically 0.1% to 2% in ready-to-use hair color products
- Regulatory status
- Approved for use in cosmetic hair dyes in the EU (Annex IV) and the US (as a color additive for hair dyes). Not approved for use in products applied to the eye area or on damaged skin.
- Common uses
- Semi-permanent hair dyes, Temporary hair rinses, Colored hair masks
- Environmental note
- As a synthetic dye, it is not biodegradable and may contribute to water pollution if not disposed of properly. Always follow local guidelines for disposal of hair dye products.
Good to know
- HC Blue No. 16 is not approved for use in products intended to be applied to the eye area, such as mascara or eyeliner.
- It is often combined with other HC dyes to create a range of cool and pastel shades.
Common questions
What is HC Blue No. 16 in beauty products?
HC Blue No. 16 is a man-made blue colorant used in hair dyes to give hair a blue or cool-toned tint. It is not intended for skincare or makeup around the eyes. Like many hair dyes, it can occasionally cause skin irritation or allergic reactions, so a patch test is recommended before full use.
What does HC Blue No. 16 do in a beauty product?
In a hair dye product, HC Blue No. 16 deposits onto the hair shaft's outer cuticle, staining it blue. Because it does not penetrate deeply, the color is semi-permanent and gradually washes out over several shampoos.
Is HC Blue No. 16 safe for most people?
HC Blue No. 16 is considered safe for use in hair dyes at typical concentrations when used as directed. The main safety concern is the potential for allergic contact dermatitis, which can be minimized by performing a patch test before each use.
Who should be careful with HC Blue No. 16?
Individuals with known allergies to hair dyes or p-phenylenediamine (PPD) People with sensitive scalps or active skin conditions on the scalp
Research sources
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.