Ingredient review
Isobutylene/Sodium Maleate Copolymer
INCI: ISOBUTYLENE/SODIUM MALEATE COPOLYMER
A synthetic polymer that helps products stay put and resist water, generally considered safe and non-irritating.
In plain English
This is a man-made ingredient that forms a thin, flexible film on your skin. It helps other ingredients stay in place and makes products more water-resistant, so your sunscreen or makeup lasts longer. Think of it like a gentle, invisible shield that doesn't clog pores or cause irritation for most people.
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
Isobutylene/Sodium Maleate 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 Isobutylene/Sodium Maleate 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 combining isobutylene and sodium maleate. It is a high-molecular-weight polymer that forms a flexible film when applied to the skin.
How it works
When applied, the copolymer dries into a continuous, flexible film that adheres to the skin. This film physically locks in other ingredients (like UV filters or pigments) and creates a barrier that resists water and sweat. It also slightly thickens the product, giving it a smooth, spreadable texture.
Pros
Boosts water resistance
Helps sunscreens and makeup stay effective even when you sweat or swim, so you don't have to reapply as often.
Improves wear time
Creates a flexible film that keeps makeup and active ingredients on the skin longer, reducing the need for touch-ups.
Cons and cautions
Can feel tacky
Some users report a slightly sticky or heavy feel on the skin, especially in high-humidity conditions.
Not natural
As a synthetic polymer, it may not fit into 'clean' or minimalist skincare routines that avoid man-made ingredients.
Best for
- Anyone using water-resistant sunscreen
- People who want long-wearing makeup
- Those with normal to oily skin who don't mind a slight film feel
Use caution if
- People who prefer completely natural or silicone-free routines
- Those with very dry skin who may find the film too drying over time
Usage tips
Safety summary
Isobutylene/Sodium Maleate Copolymer is considered safe for use in cosmetics. It has low irritation and comedogenic potential, and no significant safety concerns have been raised by regulatory bodies or dermatological research.
Research notes
Research on this specific copolymer is limited, but it belongs to a well-studied class of film-forming polymers used safely in cosmetics for decades. No published studies link it to skin sensitization or systemic toxicity at cosmetic use levels.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics in the US, EU, and many other regions. No known restrictions at typical use levels.
- Common uses
- Sun protection, Water-resistant formulas, Long-wear makeup
- Environmental note
- As a synthetic polymer, it is not biodegradable. However, it is used in small amounts and is not considered a major environmental concern compared to microplastics.
Good to know
- This ingredient is often found in combination with other film-formers like acrylates copolymer.
- It is not a preservative, but its film-forming ability can help protect other ingredients from degradation.
Common questions
What is Isobutylene/Sodium Maleate Copolymer in beauty products?
This is a man-made ingredient that forms a thin, flexible film on your skin. It helps other ingredients stay in place and makes products more water-resistant, so your sunscreen or makeup lasts longer. Think of it like a gentle, invisible shield that doesn't clog pores or cause irritation for most people.
What does Isobutylene/Sodium Maleate Copolymer do in a beauty product?
When applied, the copolymer dries into a continuous, flexible film that adheres to the skin. This film physically locks in other ingredients (like UV filters or pigments) and creates a barrier that resists water and sweat. It also slightly thickens the product, giving it a smooth, spreadable texture.
Is Isobutylene/Sodium Maleate Copolymer safe for most people?
Isobutylene/Sodium Maleate Copolymer is considered safe for use in cosmetics. It has low irritation and comedogenic potential, and no significant safety concerns have been raised by regulatory bodies or dermatological research.
Who should be careful with Isobutylene/Sodium Maleate Copolymer?
People who prefer completely natural or silicone-free routines Those with very dry skin who may find the film too drying over time
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.