Ingredient review
Polyethylene Terephthalate
INCI: POLYETHYLENE TEREPHTHALATE
A common plastic polymer that helps products form a durable, glossy film, but raises environmental concerns due to its non-biodegradable nature.
In plain English
Polyethylene terephthalate (PET) is a type of plastic often used in water bottles and clothing. In cosmetics, it is added to help products like nail polish and mascara form a smooth, long-lasting film on the skin or nails. It is generally considered safe for topical use, but it is not biodegradable and can contribute to microplastic pollution.
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
Polyethylene Terephthalate 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 Polyethylene Terephthalate.
- 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 polyester resin made from ethylene glycol and terephthalic acid, commonly used in packaging and textiles, and repurposed in cosmetics for its film-forming and thickening properties.
How it works
When applied, PET forms a thin, flexible, and durable film on the surface of the skin, nails, or hair. This film helps other ingredients adhere better, improves water resistance, and gives a glossy finish. It also increases the viscosity of liquid products, making them easier to apply evenly.
Pros
Durable film
Creates a strong, flexible film that helps nail polish and mascara last longer without chipping or flaking.
Glossy finish
Provides a high-shine, smooth appearance that enhances the look of nail and lip products.
Cons and cautions
Environmental concern
PET is a non-biodegradable plastic that can accumulate as microplastic pollution, raising ecological issues.
Synthetic feel
Some users may find products containing PET feel stiff, heavy, or less breathable on the skin or nails.
Best for
- Anyone looking for long-wearing nail polish or mascara
- People who want a glossy, durable finish in their makeup
Use caution if
- Those concerned about environmental impact of microplastics
- Individuals with very sensitive skin who prefer minimal synthetic ingredients
Usage tips
Safety summary
Polyethylene terephthalate is considered safe for use in cosmetics at typical concentrations. It is not absorbed through the skin and has low irritation and comedogenic potential. However, its environmental impact is a growing concern.
Research notes
The Cosmetic Ingredient Review (CIR) panel reviewed PET and concluded it is safe for topical use. Studies focus on its film-forming properties and lack of skin penetration. Environmental research highlights its persistence as a microplastic.
Common label clues
- Typical concentration
- Typically 1–10% in nail products, lower in other cosmetics
- Regulatory status
- Approved for use in cosmetics in the EU, US, and many other regions. The Cosmetic Ingredient Review (CIR) panel has deemed it safe for topical use at typical concentrations.
- Common uses
- Nail polishes, Mascaras, Eyeliners, Lip products
- Environmental note
- PET is not biodegradable and can persist in the environment. It is a known contributor to microplastic pollution, though recycling programs exist for packaging-grade PET.
Good to know
- PET is the same plastic used in many beverage bottles, but cosmetic-grade PET is purified and processed for safe topical use.
- Some brands are moving toward biodegradable alternatives to address environmental concerns.
Common questions
What is Polyethylene Terephthalate in beauty products?
Polyethylene terephthalate (PET) is a type of plastic often used in water bottles and clothing. In cosmetics, it is added to help products like nail polish and mascara form a smooth, long-lasting film on the skin or nails. It is generally considered safe for topical use, but it is not biodegradable and can contribute to microplastic pollution.
What does Polyethylene Terephthalate do in a beauty product?
When applied, PET forms a thin, flexible, and durable film on the surface of the skin, nails, or hair. This film helps other ingredients adhere better, improves water resistance, and gives a glossy finish. It also increases the viscosity of liquid products, making them easier to apply evenly.
Is Polyethylene Terephthalate safe for most people?
Polyethylene terephthalate is considered safe for use in cosmetics at typical concentrations. It is not absorbed through the skin and has low irritation and comedogenic potential. However, its environmental impact is a growing concern.
Who should be careful with Polyethylene Terephthalate?
Those concerned about environmental impact of microplastics Individuals with very sensitive skin who prefer minimal synthetic ingredients
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.