Ingredient review
PEI-2500
INCI: PEI-2500
PEI-2500 is a synthetic polymer that helps products spread smoothly and resist water, but it's not a star ingredient for skin health.
In plain English
PEI-2500 is a man-made ingredient that forms a thin, flexible film on your skin. This film helps other ingredients stay put longer and can make a product feel more water-resistant. It's often used in sunscreens and long-wear makeup. Think of it like a gentle, invisible shield that helps your skincare or makeup last through sweat or humidity.
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
PEI-2500 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 PEI-2500.
- 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
PEI-2500 is a synthetic polymer, specifically a polyethyleneimine with a molecular weight around 2500. It is produced through chemical synthesis and is not found in nature.
How it works
When applied to the skin, PEI-2500 forms a uniform, flexible film. This film can improve the spreadability of a product, help other ingredients adhere to the skin, and provide a degree of water resistance. It also can slightly thicken a formula, giving it a more luxurious feel.
Pros
Boosts water resistance
Helps sunscreens and makeup stay effective longer during swimming or sweating, reducing the need for frequent reapplication.
Improves texture
Creates a smooth, even application and a pleasant, non-sticky feel on the skin, making products more enjoyable to use.
Cons and cautions
Synthetic origin
As a man-made polymer, it may not be preferred by those seeking natural or 'clean' beauty products, though it is considered safe.
Limited skin benefit
PEI-2500 is a functional ingredient that improves product performance, but it does not directly moisturize, soothe, or treat the skin.
Best for
- Anyone using water-resistant sunscreens or long-wear makeup
- People who want a smooth, even application from their products
Use caution if
- Those strictly avoiding all synthetic polymers
- Individuals with known sensitivity to film-forming agents (rare)
Usage tips
Safety summary
PEI-2500 is considered safe for use in cosmetics at typical concentrations. It has low irritation and comedogenic potential. However, there is limited published research on its long-term skin absorption, so it is best used in rinse-off or leave-on products as intended.
Research notes
Safety assessments rely on general polymer toxicology and industry data. No major safety concerns have been raised by regulatory bodies. Peer-reviewed studies on this specific ingredient in cosmetics are scarce, but it is structurally similar to other approved film formers.
Common label clues
- Typical concentration
- Typically used at 0.1–2% in leave-on products
- Regulatory status
- Approved for use in cosmetics in the US (FDA) and EU (CosIng) at typical concentrations. No specific restrictions beyond general cosmetic safety requirements.
- Common uses
- Sunscreens, Water-resistant formulas, Makeup primers
- Environmental note
- As a synthetic polymer, its biodegradability is limited. It is not known to be a major environmental concern at cosmetic use levels, but it is not readily biodegradable.
Good to know
- PEI-2500 is different from other PEI variants used in industrial applications; cosmetic-grade is purified for safety.
- It is often combined with other film formers to achieve a specific texture or level of water resistance.
Common questions
What is PEI-2500 in beauty products?
PEI-2500 is a man-made ingredient that forms a thin, flexible film on your skin. This film helps other ingredients stay put longer and can make a product feel more water-resistant. It's often used in sunscreens and long-wear makeup. Think of it like a gentle, invisible shield that helps your skincare or makeup last through sweat or humidity.
What does PEI-2500 do in a beauty product?
When applied to the skin, PEI-2500 forms a uniform, flexible film. This film can improve the spreadability of a product, help other ingredients adhere to the skin, and provide a degree of water resistance. It also can slightly thicken a formula, giving it a more luxurious feel.
Is PEI-2500 safe for most people?
PEI-2500 is considered safe for use in cosmetics at typical concentrations. It has low irritation and comedogenic potential. However, there is limited published research on its long-term skin absorption, so it is best used in rinse-off or leave-on products as intended.
Who should be careful with PEI-2500?
Those strictly avoiding all synthetic polymers Individuals with known sensitivity to film-forming agents (rare)
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.