Ingredient review
Isoprene/MA/Methoxy PEG-40 Copolymer
INCI: ISOPRENE/MA/METHOXY PEG-40 COPOLYMER
A synthetic polymer that helps products stay put and resist water, but offers no active skincare benefit.
In plain English
This is a man-made ingredient that forms a thin, flexible film on your skin. It's like a clear, invisible coat that helps makeup or sunscreen stay in place longer and resist sweat or water. It doesn't moisturize or treat your skin—it's purely a performance booster for the product.
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
Isoprene/MA/Methoxy PEG-40 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 Isoprene/MA/Methoxy PEG-40 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 isoprene, maleic anhydride, and methoxy PEG-40. It's designed to create a flexible, water-resistant film on the skin.
How it works
When applied, the polymer molecules link together to form a continuous film on the skin's surface. This film helps other ingredients adhere better, reduces transfer, and improves water resistance. It also slightly thickens the product for a smoother application.
Pros
Boosts wear time
Helps makeup and sunscreen stay put for hours, reducing the need for touch-ups.
Water-resistant
Creates a barrier that resists sweat and water, ideal for active days or humid weather.
Cons and cautions
No active benefit
Does not moisturize, soothe, or treat the skin—it's purely a performance ingredient.
Synthetic and not biodegradable
Made from petrochemicals and does not break down easily in the environment, which may concern eco-conscious users.
Best for
- Anyone wanting long-lasting makeup or sunscreen
- People with oily skin who need extra staying power
Use caution if
- Those who prefer only natural or biodegradable ingredients
- Individuals with very dry or compromised skin barriers who may find films uncomfortable
Usage tips
Safety summary
Considered safe for cosmetic use at typical concentrations. Low irritation and comedogenic risk. No significant safety concerns reported in regulatory reviews.
Research notes
Limited independent research on this specific copolymer. Safety is inferred from its structural similarity to other approved film-forming polymers. No published studies on long-term skin effects.
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
- Sunscreens, Waterproof makeup, Long-wear foundations, Eye liners
- Environmental note
- As a synthetic polymer, it is not biodegradable. However, it is used in low concentrations and is not known to bioaccumulate.
Good to know
- Often found in 'waterproof' or 'long-wear' labeled products.
- Can be combined with other film-formers for even stronger resistance.
Common questions
What is Isoprene/MA/Methoxy PEG-40 Copolymer in beauty products?
This is a man-made ingredient that forms a thin, flexible film on your skin. It's like a clear, invisible coat that helps makeup or sunscreen stay in place longer and resist sweat or water. It doesn't moisturize or treat your skin—it's purely a performance booster for the product.
What does Isoprene/MA/Methoxy PEG-40 Copolymer do in a beauty product?
When applied, the polymer molecules link together to form a continuous film on the skin's surface. This film helps other ingredients adhere better, reduces transfer, and improves water resistance. It also slightly thickens the product for a smoother application.
Is Isoprene/MA/Methoxy PEG-40 Copolymer safe for most people?
Considered safe for cosmetic use at typical concentrations. Low irritation and comedogenic risk. No significant safety concerns reported in regulatory reviews.
Who should be careful with Isoprene/MA/Methoxy PEG-40 Copolymer?
Those who prefer only natural or biodegradable ingredients Individuals with very dry or compromised skin barriers who may find films uncomfortable
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.