Ingredient review
PEG-150/Stearyl Alcohol/SMDI Copolymer
INCI: PEG-150/STEARYL ALCOHOL/SMDI COPOLYMER
A synthetic polymer that helps products stay put and feel smooth, 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 helps other ingredients spread evenly and makes products like sunscreen or foundation last longer, even when you sweat or get wet. Think of it like a gentle, invisible glue that holds your makeup or sun protection in place.
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
PEG-150/Stearyl Alcohol/SMDI 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 PEG-150/Stearyl Alcohol/SMDI 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 reacting polyethylene glycol (PEG-150), stearyl alcohol, and a diisocyanate (SMDI). It is a large molecule designed to form a film on the skin.
How it works
When applied, the copolymer dries to create a thin, flexible, water-resistant film on the skin's surface. This film helps lock in other ingredients (like sunscreen filters or pigments) and improves the product's texture, making it feel silky and smooth.
Pros
Boosts water resistance
Helps sunscreen and makeup stay effective longer during swimming, sweating, or humid conditions.
Improves texture
Creates a silky, smooth feel on the skin, making products easier to apply and more pleasant to wear.
Cons and cautions
No active benefit
This ingredient is purely functional—it doesn't hydrate, soothe, or treat the skin in any way.
May require double cleansing
The film it forms can be stubborn to remove with just water or a gentle cleanser, often needing an oil-based first step.
Best for
- Anyone wanting long-lasting, water-resistant sunscreen or makeup
- People with normal to oily skin who prefer a matte finish
Use caution if
- Those who prefer lightweight, minimal-ingredient routines
- Individuals with very dry or dehydrated skin who may find film-formers uncomfortable
Usage tips
Safety summary
Generally recognized as safe for topical use in cosmetics at typical concentrations. Low irritation and comedogenic risk. No significant safety concerns reported in available literature.
Research notes
Limited peer-reviewed research specifically on this copolymer, but it is structurally similar to other film-forming polymers that have been evaluated for safety and efficacy. Its function is well-understood in cosmetic science.
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 polymers and found them safe as used.
- Common uses
- Sunscreens, Water-resistant makeup, Long-wear foundations
- Environmental note
- As a synthetic polymer, it may not be biodegradable. Its environmental impact depends on formulation and disposal methods.
Good to know
- PEG-150/Stearyl Alcohol/SMDI Copolymer is often found in 'sport' or 'water-resistant' formulas.
- It is considered safe for use in cosmetics by major regulatory bodies at typical concentrations.
Common questions
What is PEG-150/Stearyl Alcohol/SMDI Copolymer in beauty products?
This is a man-made ingredient that forms a thin, flexible film on your skin. It helps other ingredients spread evenly and makes products like sunscreen or foundation last longer, even when you sweat or get wet. Think of it like a gentle, invisible glue that holds your makeup or sun protection in place.
What does PEG-150/Stearyl Alcohol/SMDI Copolymer do in a beauty product?
When applied, the copolymer dries to create a thin, flexible, water-resistant film on the skin's surface. This film helps lock in other ingredients (like sunscreen filters or pigments) and improves the product's texture, making it feel silky and smooth.
Is PEG-150/Stearyl Alcohol/SMDI Copolymer safe for most people?
Generally recognized as safe for topical use in cosmetics at typical concentrations. Low irritation and comedogenic risk. No significant safety concerns reported in available literature.
Who should be careful with PEG-150/Stearyl Alcohol/SMDI Copolymer?
Those who prefer lightweight, minimal-ingredient routines Individuals with very dry or dehydrated skin who may 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.