Ingredient review
Polyurethane-37
INCI: Polyurethane-37
Polyurethane-37 is a synthetic film-former that helps makeup and sunscreen stay put without feeling heavy or sticky.
In plain English
Polyurethane-37 is a man-made polymer that forms a thin, flexible, water-resistant film on your skin or hair. Think of it like a very lightweight, breathable plastic wrap that helps products last longer, resist sweat and water, and keep ingredients in place. It's commonly found in long-wear makeup, waterproof sunscreens, and styling products.
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
Polyurethane-37 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 Polyurethane-37.
- 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
Polyurethane-37 is a synthetic polymer belonging to the polyurethane family. It is created through a chemical reaction between polyols and diisocyanates, resulting in a flexible, durable film. In cosmetics, it is used as a film former and viscosity increasing agent.
How it works
When applied, the water or solvent in the product evaporates, leaving behind a thin, continuous film of Polyurethane-37 on the skin or hair. This film is flexible, so it moves with your skin without cracking, and it is water-resistant, helping the product stay intact longer. It also helps suspend other ingredients like pigments or UV filters evenly.
Pros
Long-lasting wear
Helps makeup and sunscreen resist sweat, water, and rubbing, so you don't have to reapply as often.
Lightweight feel
Unlike older film-formers, Polyurethane-37 creates a flexible film that doesn't feel stiff or heavy on the skin.
Cons and cautions
Synthetic origin
It is a man-made polymer, which may be a turn-off for those seeking natural or minimal-ingredient routines.
Removal difficulty
Because it forms a water-resistant film, you may need an oil-based cleanser or micellar water to fully remove it without irritation.
Best for
- People who want long-wearing makeup or waterproof sunscreen
- Those with normal to oily skin looking for a matte, stay-put finish
Use caution if
- Individuals who prefer exclusively natural or plant-based ingredients
- Those with very dry or sensitive skin who may find film-formers too occlusive
Usage tips
Safety summary
Polyurethane-37 has a low irritation and comedogenic risk. It is considered safe for use in cosmetics at typical concentrations. Some individuals with very sensitive skin may experience mild tightness or dryness.
Research notes
Research on Polyurethane-37 specifically is limited, but the broader class of polyurethane film-formers is well-studied and considered safe for topical use. Safety assessments by the Cosmetic Ingredient Review (CIR) panel have found no significant concerns.
Common label clues
- Typical concentration
- 1% to 10%
- Regulatory status
- Approved for use in cosmetics in the US (FDA), EU (CosIng), and many other regions. It is not a restricted ingredient.
- Common uses
- Long-wear foundations, Waterproof mascaras, Sunscreens, Hair styling 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
- Polyurethane-37 is considered safe by major cosmetic safety panels when used as directed.
- It is not the same as polyurethane used in foams or coatings — cosmetic-grade versions are specifically designed for skin contact.
Common questions
What is Polyurethane-37 in beauty products?
Polyurethane-37 is a man-made polymer that forms a thin, flexible, water-resistant film on your skin or hair. Think of it like a very lightweight, breathable plastic wrap that helps products last longer, resist sweat and water, and keep ingredients in place. It's commonly found in long-wear makeup, waterproof sunscreens, and styling products.
What does Polyurethane-37 do in a beauty product?
When applied, the water or solvent in the product evaporates, leaving behind a thin, continuous film of Polyurethane-37 on the skin or hair. This film is flexible, so it moves with your skin without cracking, and it is water-resistant, helping the product stay intact longer. It also helps suspend other ingredients like pigments or UV filters evenly.
Is Polyurethane-37 safe for most people?
Polyurethane-37 has a low irritation and comedogenic risk. It is considered safe for use in cosmetics at typical concentrations. Some individuals with very sensitive skin may experience mild tightness or dryness.
Who should be careful with Polyurethane-37?
Individuals who prefer exclusively natural or plant-based ingredients Those with very dry or sensitive skin who may find film-formers too occlusive
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.