Ingredient review
Isobutylene/Ethylmaleimide/Hydroxyethylmaleimide Copolymer
INCI: ISOBUTYLENE/ETHYLMALEIMIDE/HYDROXYETHYLMALEIMIDE COPOLYMER
A synthetic polymer that helps makeup and sunscreen stay put longer, but offers no active skincare benefit.
In plain English
This is a man-made ingredient that forms a thin, flexible film on your skin. Think of it like an invisible, breathable shield that helps makeup resist sweat, water, and smudging. It doesn't treat or change your skin—it just makes products last longer and feel smoother.
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/Ethylmaleimide/Hydroxyethylmaleimide 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/Ethylmaleimide/Hydroxyethylmaleimide 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 made from isobutylene and two types of maleimide monomers. It is designed to create a flexible, water-resistant film when applied to the skin or hair.
How it works
When the product dries, the polymer molecules link together into a continuous film. This film physically blocks water and oil from disturbing the product underneath, improving wear time and water resistance. It also gives a smooth, silky feel to the formula.
Pros
Boosts wear time
Creates a flexible film that helps makeup resist smudging, sweat, and water for hours.
Smooth finish
Gives a silky, non-greasy feel that helps products glide on and stay put without caking.
Cons and cautions
No skincare benefit
This ingredient only improves texture and longevity—it doesn't hydrate, soothe, or treat the skin.
Potential tightness
In high concentrations, the film can feel tight or uncomfortable on very dry or sensitive skin.
Best for
- Anyone wanting long-lasting, waterproof makeup or sunscreen
- People with oily or combination skin who prefer a matte, stay-put finish
Use caution if
- Those with very dry or dehydrated skin may find film-forming polymers uncomfortable or too tightening
Usage tips
Safety summary
Low irritation and comedogenic risk. Safe for most skin types when used in rinse-off or leave-on products at typical concentrations. No significant safety concerns reported in cosmetic use.
Research notes
Limited independent peer-reviewed studies on this specific copolymer, but it is structurally similar to other well-studied film-forming polymers used safely in cosmetics for decades. Safety assessments rely on analog data and industry experience.
Common label clues
- Typical concentration
- 1–10% depending on the formula
- Regulatory status
- Approved for use in cosmetics in the EU, US, and many other regions. No known restrictions at typical use levels.
- Common uses
- Long-wear foundations, Waterproof mascaras, Sunscreens, Lip products
- Environmental note
- As a synthetic polymer, it is not biodegradable. However, it is used in small amounts and is not known to bioaccumulate significantly.
Good to know
- This polymer is considered safe for use in cosmetics by major regulatory bodies when used as intended.
- It is often found in 'waterproof' or '24-hour wear' formulas.
Common questions
What is Isobutylene/Ethylmaleimide/Hydroxyethylmaleimide Copolymer in beauty products?
This is a man-made ingredient that forms a thin, flexible film on your skin. Think of it like an invisible, breathable shield that helps makeup resist sweat, water, and smudging. It doesn't treat or change your skin—it just makes products last longer and feel smoother.
What does Isobutylene/Ethylmaleimide/Hydroxyethylmaleimide Copolymer do in a beauty product?
When the product dries, the polymer molecules link together into a continuous film. This film physically blocks water and oil from disturbing the product underneath, improving wear time and water resistance. It also gives a smooth, silky feel to the formula.
Is Isobutylene/Ethylmaleimide/Hydroxyethylmaleimide Copolymer safe for most people?
Low irritation and comedogenic risk. Safe for most skin types when used in rinse-off or leave-on products at typical concentrations. No significant safety concerns reported in cosmetic use.
Who should be careful with Isobutylene/Ethylmaleimide/Hydroxyethylmaleimide Copolymer?
Those with very dry or dehydrated skin may find film-forming polymers uncomfortable or too tightening
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.