Ingredient review
Polyurethane-33
INCI: Polyurethane-33
Polyurethane-33 is a synthetic film former that helps makeup and sunscreen stay put longer, but it may feel heavy on some skin types.
In plain English
Polyurethane-33 is a plastic-like polymer added to cosmetics to create a thin, flexible film on your skin or hair. Think of it like a clear, invisible glove that helps makeup resist sweat, water, and rubbing. It's commonly found in long-wear foundations, waterproof mascaras, and sunscreens to improve durability. While generally safe and non-irritating, it can feel a bit heavy or tight on very dry or sensitive skin.
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-33 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-33.
- 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-33 is a synthetic polymer belonging to the polyurethane family. It is created by reacting diisocyanates with polyols, resulting in a flexible, film-forming material. In cosmetics, it is used as a film former and viscosity increasing agent.
How it works
When applied, Polyurethane-33 forms a continuous, flexible film on the skin or hair surface. This film acts as a barrier that locks in other ingredients, resists water and sweat, and helps the product adhere longer. It also thickens the product's texture for easier application.
Pros
Boosts wear time
Helps makeup and sunscreen stay put for hours, even in humid or sweaty conditions.
Water-resistant barrier
Creates a flexible film that repels water and sweat, ideal for active lifestyles or swimming.
Cons and cautions
Can feel heavy
On dry or sensitive skin, the film may feel tight or uncomfortable, especially if layered.
Requires double cleansing
The film is not easily removed with water alone; an oil-based cleanser or micellar water is often needed.
Best for
- People who want long-wearing, waterproof makeup
- Those who use water-resistant sunscreens for outdoor activities
Use caution if
- Individuals with very dry or sensitive skin who find film formers uncomfortable
Usage tips
Safety summary
Polyurethane-33 is considered safe for cosmetic use at typical concentrations. It has low irritation and comedogenic potential, but individuals with very dry or sensitive skin may find it uncomfortable. Always patch test new products.
Research notes
Polyurethane-33 is widely used in cosmetics for its film-forming properties. Safety assessments by the CIR panel and other bodies have not identified significant health risks at typical use levels. Most evidence comes from industry safety data rather than independent clinical studies.
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 evaluated polyurethane polymers and found them safe at typical concentrations.
- Common uses
- Long-wear foundations, Waterproof mascaras, Sunscreens, Hair styling gels
- Environmental note
- As a synthetic polymer, Polyurethane-33 is not biodegradable. Its environmental impact depends on formulation and disposal, but it is not known to bioaccumulate significantly.
Good to know
- Polyurethane-33 is considered safe by the Cosmetic Ingredient Review (CIR) panel at typical use levels.
- It is not the same as polyurethane used in industrial coatings; cosmetic-grade polyurethanes are specially purified.
Common questions
What is Polyurethane-33 in beauty products?
Polyurethane-33 is a plastic-like polymer added to cosmetics to create a thin, flexible film on your skin or hair. Think of it like a clear, invisible glove that helps makeup resist sweat, water, and rubbing. It's commonly found in long-wear foundations, waterproof mascaras, and sunscreens to improve durability. While generally safe and non-irritating, it can feel a bit heavy or tight on very dry or sensitive skin.
What does Polyurethane-33 do in a beauty product?
When applied, Polyurethane-33 forms a continuous, flexible film on the skin or hair surface. This film acts as a barrier that locks in other ingredients, resists water and sweat, and helps the product adhere longer. It also thickens the product's texture for easier application.
Is Polyurethane-33 safe for most people?
Polyurethane-33 is considered safe for cosmetic use at typical concentrations. It has low irritation and comedogenic potential, but individuals with very dry or sensitive skin may find it uncomfortable. Always patch test new products.
Who should be careful with Polyurethane-33?
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.