Ingredient review
Phthalic Anhydride Copolymer
INCI: PHTHALIC ANHYDRIDE/BUTYL BENZOIC ACID/PROPYLENE GLYCOL COPOLYMER
A synthetic film-former that helps makeup and hair products last longer, but offers no skincare benefit and may feel heavy on some skin types.
In plain English
This ingredient is a plastic-like polymer that creates a thin, flexible film on skin, hair, or nails. It helps products like mascara, foundation, and hair gel stay put longer and resist water or sweat. Think of it as a clear, invisible coating that improves wear time but doesn't actively hydrate or treat the skin.
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
Phthalic Anhydride Copolymer 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 Phthalic Anhydride Copolymer.
- 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
A synthetic copolymer created by reacting phthalic anhydride, butyl benzoic acid, and propylene glycol. It belongs to a class of ingredients called film-formers, which are common in long-wear and waterproof cosmetics.
How it works
When applied, the copolymer dries to form a continuous, flexible film on the surface. This film helps other ingredients (like pigments) adhere better, reduces smudging, and creates a water-resistant barrier. It also thickens the product's texture, making it easier to apply evenly.
Pros
Boosts wear time
Creates a flexible film that helps makeup and hair products resist smudging, fading, and water for hours.
Improves texture
Thickens the product for a smooth, even application, especially in nail polishes and mascaras.
Cons and cautions
No skincare benefit
This ingredient is purely functional—it doesn't hydrate, soothe, or treat the skin in any way.
Can feel heavy
On dry or sensitive skin, the film may feel tight or uncomfortable, and it requires double cleansing to remove fully.
Best for
- People who want long-wearing, waterproof makeup
- Those who use nail polish and want a durable finish
Use caution if
- Individuals with very dry or sensitive skin who prefer lightweight, breathable formulas
Usage tips
Safety summary
Generally considered safe for topical use in cosmetics. It is not absorbed into the skin and has low irritation potential. However, it offers no skincare benefits and may feel uncomfortable on very dry or sensitive skin. Always remove thoroughly to avoid buildup.
Research notes
There is limited published research specifically on this copolymer, but the broader class of film-forming polymers has been reviewed by the Cosmetic Ingredient Review (CIR) panel and deemed safe for cosmetic use at typical concentrations. No significant toxicity or sensitization concerns have been identified.
Common label clues
- Typical concentration
- Typically 1–10% in leave-on formulas
- Regulatory status
- Approved for use in cosmetics in the US (FDA), EU, and many other regions. The Cosmetic Ingredient Review (CIR) panel has evaluated similar film-forming polymers and found them safe at typical use levels.
- Common uses
- Nail polishes, Hair styling products, Waterproof mascaras, Long-wear foundations
- Environmental note
- As a synthetic polymer, it is not biodegradable and may contribute to microplastic pollution. Some brands are moving toward biodegradable alternatives.
Good to know
- This ingredient is not related to phthalates, which are a different class of chemicals often avoided in cosmetics.
- It is commonly found in 'long-wear' or '24-hour' makeup claims.
- The polymer is not absorbed into the skin—it sits on the surface.
Common questions
What is Phthalic Anhydride Copolymer in beauty products?
This ingredient is a plastic-like polymer that creates a thin, flexible film on skin, hair, or nails. It helps products like mascara, foundation, and hair gel stay put longer and resist water or sweat. Think of it as a clear, invisible coating that improves wear time but doesn't actively hydrate or treat the skin.
What does Phthalic Anhydride Copolymer do in a beauty product?
When applied, the copolymer dries to form a continuous, flexible film on the surface. This film helps other ingredients (like pigments) adhere better, reduces smudging, and creates a water-resistant barrier. It also thickens the product's texture, making it easier to apply evenly.
Is Phthalic Anhydride Copolymer safe for most people?
Generally considered safe for topical use in cosmetics. It is not absorbed into the skin and has low irritation potential. However, it offers no skincare benefits and may feel uncomfortable on very dry or sensitive skin. Always remove thoroughly to avoid buildup.
Who should be careful with Phthalic Anhydride Copolymer?
Individuals with very dry or sensitive skin who prefer lightweight, breathable formulas
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.