Ingredient review
Sodium Trimethylpentene/MA Copolymer
INCI: SODIUM TRIMETHYLPENTENE/MA COPOLYMER
A synthetic film-former that helps skincare and sunscreen stay put longer, especially in water-resistant formulas.
In plain English
This ingredient is a synthetic polymer that forms a thin, flexible film on your skin. Think of it like a very lightweight, invisible shield that helps other ingredients (like sunscreen actives or moisturizers) stay in place longer, even when you sweat or get wet. It's not absorbed into the skin but sits on the surface to improve product durability and feel.
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
Sodium Trimethylpentene/MA 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 Sodium Trimethylpentene/MA 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
Sodium Trimethylpentene/MA Copolymer is a synthetic polymer derived from maleic anhydride and a specific hydrocarbon monomer. It is neutralized with sodium to make it water-dispersible and is commonly used as a film-forming agent in cosmetics.
How it works
When applied, the copolymer molecules link together as the water evaporates, forming a continuous, flexible film on the skin's surface. This film helps lock in other ingredients, reduces water loss from the product, and improves resistance to rubbing off or washing away.
Pros
Boosts water resistance
Helps sunscreens and makeup stay effective longer during swimming, sweating, or humid conditions.
Improves skin feel
Creates a smooth, silky finish without heavy greasiness, making products more pleasant to wear.
Cons and cautions
Synthetic origin
Derived from petrochemicals, which may not align with natural or minimalist skincare preferences.
Potential tightness
On very dry or dehydrated skin, the film can feel slightly tight or uncomfortable after application.
Best for
- Anyone using water-resistant sunscreen or long-wear makeup
- People with normal to oily skin who want products to stay put
Use caution if
- Those who prefer only natural or plant-derived ingredients
- Individuals with very dry or sensitive skin who find film-formers uncomfortable
Usage tips
Safety summary
Sodium Trimethylpentene/MA Copolymer is considered safe for topical use in cosmetics. It is not absorbed into the skin, has low irritation and comedogenic potential, and is well-tolerated by most skin types.
Research notes
Safety assessments for similar maleic anhydride copolymers support their use as film-formers in cosmetics. Specific studies on this exact polymer are limited, but its chemical class is well-established as safe and effective.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics in the US (FDA), EU (CosIng), and other major markets. No concentration restrictions are typically specified for this polymer.
- Common uses
- Sunscreens, Water-resistant lotions, Long-wear makeup, Moisturizers
- 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
- This ingredient is often found in combination with other film-formers to fine-tune water resistance and texture.
- It is considered safe for use in cosmetics by major regulatory bodies when used as directed.
Common questions
What is Sodium Trimethylpentene/MA Copolymer in beauty products?
This ingredient is a synthetic polymer that forms a thin, flexible film on your skin. Think of it like a very lightweight, invisible shield that helps other ingredients (like sunscreen actives or moisturizers) stay in place longer, even when you sweat or get wet. It's not absorbed into the skin but sits on the surface to improve product durability and feel.
What does Sodium Trimethylpentene/MA Copolymer do in a beauty product?
When applied, the copolymer molecules link together as the water evaporates, forming a continuous, flexible film on the skin's surface. This film helps lock in other ingredients, reduces water loss from the product, and improves resistance to rubbing off or washing away.
Is Sodium Trimethylpentene/MA Copolymer safe for most people?
Sodium Trimethylpentene/MA Copolymer is considered safe for topical use in cosmetics. It is not absorbed into the skin, has low irritation and comedogenic potential, and is well-tolerated by most skin types.
Who should be careful with Sodium Trimethylpentene/MA Copolymer?
Those who prefer only natural or plant-derived ingredients Individuals 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.