Ingredient review
Stearyl/lauryl Methacrylate Crosspolymer
INCI: STEARYL/LAURYL METHACRYLATE CROSSPOLYMER
A synthetic polymer that helps products stay put and resist water, but offers no active skincare benefit.
In plain English
This ingredient is a type of plastic-like polymer that forms a thin, flexible film on your skin. It's used in products like sunscreen and long-lasting makeup to help them stay in place longer and resist water or sweat. Think of it as a clear, invisible shield that holds the product where you put it. It doesn't treat or change your skin—it just improves how the product feels and performs.
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
Stearyl/lauryl Methacrylate Crosspolymer 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 Stearyl/lauryl Methacrylate Crosspolymer.
- 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 crosslinked polymer made from stearyl and lauryl methacrylate monomers. Crosslinking creates a network structure that gives the polymer its film-forming and thickening properties.
How it works
When applied, the polymer dries to form a continuous, flexible film on the skin. This film helps other ingredients (like UV filters or pigments) adhere evenly and resist being washed or rubbed off. It also slightly thickens the product's texture, making it feel smoother during application.
Pros
Boosts wear time
Helps sunscreen and makeup stay put for hours, even in heat or humidity, so you don't need to reapply as often.
Enhances water resistance
Forms a barrier that prevents product from washing off easily, making it ideal for swimming or sweaty activities.
Cons and cautions
No active benefit
This ingredient only improves product performance—it doesn't hydrate, soothe, or treat your skin in any way.
Environmental persistence
As a synthetic polymer, it is not biodegradable and may accumulate in the environment, which is a concern for eco-conscious consumers.
Best for
- People who want long-wearing makeup or water-resistant sunscreen
- Those with normal to oily skin who prefer a matte finish
Use caution if
- Those who prefer only natural or biodegradable ingredients
- People with very dry or sensitive skin who find film-formers uncomfortable
Usage tips
Safety summary
Generally recognized as safe for topical use at typical concentrations. Low irritation and comedogenic risk. No known systemic toxicity from cosmetic use.
Research notes
Safety data is based on analogy to similar methacrylate polymers reviewed by the CIR panel. No specific human or animal studies on this exact crosspolymer were found, but the class is well-tolerated.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics in the US, EU, and many other regions. The Cosmetic Ingredient Review (CIR) panel has reviewed similar methacrylate crosspolymers and found them safe as used.
- Common uses
- Sunscreens, Long-wear makeup, Water-resistant formulas
- Environmental note
- As a non-biodegradable synthetic polymer, it may contribute to microplastic pollution. Some brands are moving toward biodegradable alternatives.
Good to know
- This polymer is often used in combination with UV filters to improve sunscreen efficacy and photostability.
- It is considered safe for use in cosmetics by major regulatory bodies at typical concentrations.
Common questions
What is Stearyl/lauryl Methacrylate Crosspolymer in beauty products?
This ingredient is a type of plastic-like polymer that forms a thin, flexible film on your skin. It's used in products like sunscreen and long-lasting makeup to help them stay in place longer and resist water or sweat. Think of it as a clear, invisible shield that holds the product where you put it. It doesn't treat or change your skin—it just improves how the product feels and performs.
What does Stearyl/lauryl Methacrylate Crosspolymer do in a beauty product?
When applied, the polymer dries to form a continuous, flexible film on the skin. This film helps other ingredients (like UV filters or pigments) adhere evenly and resist being washed or rubbed off. It also slightly thickens the product's texture, making it feel smoother during application.
Is Stearyl/lauryl Methacrylate Crosspolymer safe for most people?
Generally recognized as safe for topical use at typical concentrations. Low irritation and comedogenic risk. No known systemic toxicity from cosmetic use.
Who should be careful with Stearyl/lauryl Methacrylate Crosspolymer?
Those who prefer only natural or biodegradable ingredients People with very dry or sensitive skin who find film-formers 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.