Ingredient review
Butyl Benzoic Acid Copolymer
INCI: BUTYL BENZOIC ACID/PHTHALIC ANHYDRIDE/TRIMETHYLOLETHANE COPOLYMER
A synthetic film-former that helps products stay put and resist water, but offers no direct skin benefit.
In plain English
This ingredient is a plastic-like polymer that dries down to form a thin, flexible film on your skin or hair. Think of it like a clear, invisible raincoat that helps makeup last longer or keeps sunscreen from washing off. It doesn't moisturize or treat anything—it's purely a functional ingredient for product performance.
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
Butyl Benzoic Acid 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 Butyl Benzoic Acid 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 butyl benzoic acid, phthalic anhydride, and trimethylolethane. It belongs to a class of ingredients called film-formers, which are widely used in cosmetics to improve wear and water resistance.
How it works
When applied, the copolymer molecules spread out and then link together as the solvent (water or alcohol) evaporates, forming a continuous, flexible film. This film physically blocks water and sebum from breaking down the product, helping it stay intact longer.
Pros
Boosts water resistance
Helps sunscreen and makeup stay effective even when you sweat or get wet, reducing the need for frequent reapplication.
Extends wear time
Creates a flexible barrier that keeps foundation, eyeliner, or lip color from fading or smudging throughout the day.
Cons and cautions
No skincare benefit
This ingredient does not hydrate, soothe, or treat the skin—it only improves product texture and longevity.
Can be hard to remove
The film it forms may require an oil-based cleanser or double cleansing to fully break down, which can be inconvenient.
Best for
- People who want long-wearing, water-resistant makeup or sunscreen
- Those with oily skin who need products that stay put
Use caution if
- Anyone with very dry or sensitive skin who prefers minimal film-formers
Usage tips
Safety summary
Generally recognized as safe for topical use in cosmetics. Low irritation and comedogenic risk. No significant safety concerns at typical concentrations.
Research notes
Limited peer-reviewed studies specifically on this copolymer, but film-forming polymers as a class are well-studied for safety and function. The CIR and EU SCCS have reviewed similar ingredients and found them safe.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics in the EU, US, and other major markets. The Cosmetic Ingredient Review (CIR) panel has evaluated similar film-forming polymers and found them safe at typical use levels.
- Common uses
- Sunscreens, Waterproof makeup, Long-wear foundations, Hair styling products
- Environmental note
- As a synthetic polymer, it may not be biodegradable. However, it is used in low concentrations and is not known to bioaccumulate significantly.
Good to know
- This ingredient is often found in 'waterproof' or 'long-wear' labeled products.
- It is considered safe for use in cosmetics at typical concentrations by major regulatory bodies.
Common questions
What is Butyl Benzoic Acid Copolymer in beauty products?
This ingredient is a plastic-like polymer that dries down to form a thin, flexible film on your skin or hair. Think of it like a clear, invisible raincoat that helps makeup last longer or keeps sunscreen from washing off. It doesn't moisturize or treat anything—it's purely a functional ingredient for product performance.
What does Butyl Benzoic Acid Copolymer do in a beauty product?
When applied, the copolymer molecules spread out and then link together as the solvent (water or alcohol) evaporates, forming a continuous, flexible film. This film physically blocks water and sebum from breaking down the product, helping it stay intact longer.
Is Butyl Benzoic Acid Copolymer safe for most people?
Generally recognized as safe for topical use in cosmetics. Low irritation and comedogenic risk. No significant safety concerns at typical concentrations.
Who should be careful with Butyl Benzoic Acid Copolymer?
Anyone with very dry or sensitive skin who prefers minimal film-formers
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.