Ingredient review
Red 33 (CI 12420)
INCI: CI 12420
A widely used synthetic dye that adds vibrant red color to cosmetics, generally considered safe at low concentrations but may cause irritation in sensitive individuals.
In plain English
CI 12420, also known as Red 33, is a man-made dye that gives a bright red or pink color to makeup and skincare products. It's added in tiny amounts to make products look more appealing, but it doesn't do anything for your skin's health. Think of it like food coloring for your cosmetics.
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
Red 33 (CI 12420) 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 Red 33 (CI 12420).
- 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
CI 12420 is a synthetic organic pigment belonging to the monoazo dye family. It is produced through chemical synthesis and is approved for use in cosmetics in many countries, including the US (as D&C Red No. 33) and the EU.
How it works
It works by absorbing and reflecting specific wavelengths of light, which creates the perception of a red color. In a cosmetic product, it is mixed into the formula to impart a uniform, stable color that doesn't easily fade or bleed.
Pros
Vibrant color payoff
Gives a bright, consistent red hue that stays true in various lighting conditions, making it a favorite for lipsticks and blushes.
Good stability
Resists fading from light and heat, so your makeup color stays fresh longer compared to some natural dyes.
Cons and cautions
Potential irritant
Can cause contact dermatitis or irritation in people with sensitive skin or allergies to synthetic dyes, especially around the eyes or lips.
Not natural
Synthetic origin may be a turn-off for those seeking plant-based or naturally derived ingredients, and it doesn't offer any skincare benefits.
Best for
- Anyone looking for a bold, consistent red color in their makeup
- People who are not sensitive to synthetic dyes
Use caution if
- Individuals with known allergies or sensitivities to synthetic dyes
- Those seeking exclusively natural or 'clean' cosmetic ingredients
Usage tips
Safety summary
CI 12420 is considered safe for use in cosmetics at regulated concentrations by major health authorities like the FDA and the European Commission. However, it can cause allergic reactions or irritation in sensitive individuals, so patch testing is recommended.
Research notes
Studies indicate that CI 12420 has low acute toxicity and is not a significant skin sensitizer for the general population. Some research has raised concerns about potential impurities like aniline, but regulatory limits ensure these are kept to safe levels.
Common label clues
- Typical concentration
- Typically used at very low concentrations (less than 1%) to achieve desired color.
- Regulatory status
- Approved for use in cosmetics in the US (FDA) and EU (EC) with concentration limits for certain product types. Always used within safe limits in regulated products.
- Common uses
- Lipsticks, Blushes, Eye shadows, Nail polishes, Soaps, Bath products
- Environmental note
- As a synthetic dye, it is not biodegradable and may accumulate in water systems if not properly filtered during manufacturing. However, cosmetic use contributes minimal environmental impact compared to industrial dyeing.
Good to know
- In the US, CI 12420 is listed as D&C Red No. 33 and is approved for use in cosmetics and drugs.
- It is often combined with other dyes to create custom shades like coral or berry.
- The 'CI' stands for Colour Index, an international numbering system for dyes and pigments.
Common questions
What is Red 33 (CI 12420) in beauty products?
CI 12420, also known as Red 33, is a man-made dye that gives a bright red or pink color to makeup and skincare products. It's added in tiny amounts to make products look more appealing, but it doesn't do anything for your skin's health. Think of it like food coloring for your cosmetics.
What does Red 33 (CI 12420) do in a beauty product?
It works by absorbing and reflecting specific wavelengths of light, which creates the perception of a red color. In a cosmetic product, it is mixed into the formula to impart a uniform, stable color that doesn't easily fade or bleed.
Is Red 33 (CI 12420) safe for most people?
CI 12420 is considered safe for use in cosmetics at regulated concentrations by major health authorities like the FDA and the European Commission. However, it can cause allergic reactions or irritation in sensitive individuals, so patch testing is recommended.
Who should be careful with Red 33 (CI 12420)?
Individuals with known allergies or sensitivities to synthetic dyes Those seeking exclusively natural or 'clean' cosmetic ingredients
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.