Ingredient review

Polyurethane-43

INCI: Polyurethane-43

Polyurethane-43 is a synthetic film former that helps makeup and sunscreen stay put longer, but it offers no active skincare benefits.

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In plain English

Polyurethane-43 is a plastic-like ingredient that dries down into a flexible, invisible film on your skin or hair. Think of it like a very thin, breathable raincoat — it helps makeup resist sweat and water, and it can make hair products hold their shape. It is not absorbed into the skin and is generally considered safe, but it is purely a performance ingredient with no moisturizing or anti-aging properties.

Review score

Safety, usefulness, and evidence

3.5Good
3.5/ 5

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
How reviews are scored

Quick decision guide

Useful, but context matters

Polyurethane-43 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.

  1. Step 1Start with the score, then check the irritation and clogging risk before judging Polyurethane-43.
  2. Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
  3. 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

low

Less likely to sting, burn, or bother most users, though sensitive skin can still react.

Clogging risk

low

Less likely to feel heavy or contribute to clogged pores for most skin types.

Evidence level

moderate

There is useful support, but formula details and claim strength still matter.

What it is

Polyurethane-43 is a synthetic polymer belonging to the polyurethane family. It is created in a lab by reacting polyols with isocyanates, then processed into a form suitable for cosmetics. It is designed to form a continuous, flexible film when applied to skin or hair.

How it works

When the product containing Polyurethane-43 is applied and the water or solvent evaporates, the polymer molecules link together to form a thin, elastic film. This film physically blocks water and oil from reaching the surface, improving the wear time of makeup and the water resistance of sunscreens. On hair, it coats each strand to hold a style and reduce frizz.

Pros

Long-lasting wear

Creates a durable film that helps makeup and sunscreen resist sweat, water, and rubbing, so you need fewer touch-ups.

Flexible feel

Unlike some older film formers, Polyurethane-43 dries to a flexible film that moves with your skin, reducing the risk of cracking or flaking.

Cons and cautions

No skincare benefit

It is purely a performance ingredient — it does not moisturize, soothe, or protect the skin in any active way.

Removal can be tricky

Because it forms a water-resistant film, you may need an oil-based or dual-phase cleanser to fully remove it, especially from around the eyes.

Best for

  • People who want long-wearing, transfer-resistant makeup
  • Those who need water-resistant sunscreens for outdoor activities or swimming

Use caution if

  • Individuals with very dry or sensitive skin who prefer lightweight, breathable formulas

Usage tips

Use an oil-based cleanser or micellar water to thoroughly remove products containing Polyurethane-43 at the end of the day.
Layer it over a good moisturizer if you have dry skin, as the film can sometimes feel slightly tightening.

Safety summary

Polyurethane-43 is considered safe for use in cosmetics at typical concentrations. It is not absorbed into the skin, has low irritation and comedogenic potential, and is well-tolerated by most skin types. However, it is a synthetic film former with no active benefits.

Research notes

Safety assessments by the Cosmetic Ingredient Review (CIR) and the European Chemicals Agency (ECHA) support the use of polyurethane polymers in cosmetics. Most data comes from industry studies and regulatory reviews rather than independent clinical trials.

Common label clues

Typical concentration
1% to 10%
Regulatory status
Approved for use in cosmetics in the US, EU, and many other regions. The Cosmetic Ingredient Review (CIR) panel has reviewed similar polyurethane polymers and found them safe as used.
Common uses
Long-wear foundations, Waterproof mascaras, Sunscreens, Hair styling products
Environmental note
As a synthetic polymer, Polyurethane-43 is not biodegradable. Its environmental impact depends on how it is filtered during wastewater treatment, but it is not known to bioaccumulate.

Good to know

  • Polyurethane-43 is often used in 'clean' or 'non-toxic' brands as an alternative to older film formers like acrylates.
  • It is not the same as polyurethane foam or industrial polyurethane — the cosmetic version is specially purified and safe for topical use.

Common questions

What is Polyurethane-43 in beauty products?

Polyurethane-43 is a plastic-like ingredient that dries down into a flexible, invisible film on your skin or hair. Think of it like a very thin, breathable raincoat — it helps makeup resist sweat and water, and it can make hair products hold their shape. It is not absorbed into the skin and is generally considered safe, but it is purely a performance ingredient with no moisturizing or anti-aging properties.

What does Polyurethane-43 do in a beauty product?

When the product containing Polyurethane-43 is applied and the water or solvent evaporates, the polymer molecules link together to form a thin, elastic film. This film physically blocks water and oil from reaching the surface, improving the wear time of makeup and the water resistance of sunscreens. On hair, it coats each strand to hold a style and reduce frizz.

Is Polyurethane-43 safe for most people?

Polyurethane-43 is considered safe for use in cosmetics at typical concentrations. It is not absorbed into the skin, has low irritation and comedogenic potential, and is well-tolerated by most skin types. However, it is a synthetic film former with no active benefits.

Who should be careful with Polyurethane-43?

Individuals with very dry or sensitive skin who prefer lightweight, breathable formulas

Research sources

Cosmetic Ingredient Review - Safety Assessment of Polyurethane PolymersOpenEuropean Chemicals Agency - Polyurethane-43 InformationOpenPubMed - Film-forming polymers in cosmeticsOpen

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.