Ingredient review
Lithium Oxidized Polyethylene
INCI: LITHIUM OXIDIZED POLYETHYLENE
A synthetic film-former that helps products stay put, but with limited research on long-term skin effects.
In plain English
This is a man-made ingredient that creates a thin, invisible film on your skin. It's mainly used to help sunscreen or makeup resist water and sweat, so they last longer. Think of it like a gentle, breathable plastic wrap that helps your product stay in place without feeling heavy.
Review score
Safety, usefulness, and evidence
Useful in the right context, but not low-maintenance
The evidence base is still emerging, so marketing claims deserve extra caution.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- synthetic
- Evidence
- emerging
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Read the cautions before using
Lithium Oxidized Polyethylene 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 Lithium Oxidized Polyethylene.
- 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
emergingThe ingredient may be promising, but claims should be treated more cautiously.
What it is
Lithium Oxidized Polyethylene is a synthetic polymer derived from polyethylene that has been oxidized and neutralized with lithium. It is a white to off-white powder that forms a flexible film when applied to the skin.
How it works
When applied, the ingredient dries down to form a continuous, water-resistant film on the skin's surface. This film helps lock in other active ingredients and prevents them from being washed away by water or sweat. It also gives a smooth, silky feel to the product.
Pros
Boosts water resistance
Helps sunscreens and makeup stay effective even when you sweat or swim, so you don't have to reapply as often.
Smooth, non-greasy feel
Creates a silky, lightweight film that doesn't feel sticky or heavy on the skin, making it pleasant to wear.
Cons and cautions
Limited safety research
There are few published studies on how this specific ingredient behaves with repeated daily use on skin, so its long-term effects are not well understood.
Environmental concerns
As a synthetic polymer, it is not biodegradable and may contribute to microplastic pollution when washed off into waterways.
Best for
- People who need water-resistant sunscreens for swimming or sweating
- Anyone wanting long-wear makeup that stays put through the day
Use caution if
- Those with very sensitive or reactive skin who prefer minimal synthetic ingredients
Usage tips
Safety summary
Generally considered safe for topical use at low concentrations, but long-term safety data is limited. It has low irritation and comedogenic potential based on available information.
Research notes
There are no major peer-reviewed studies specifically on Lithium Oxidized Polyethylene. Its safety is inferred from similar polyethylene-based film-formers, which have been used in cosmetics for decades with few reported adverse effects.
Common label clues
- Typical concentration
- 0.1% to 5%
- Regulatory status
- Approved for use in cosmetics in the US and EU, but not specifically reviewed by the Cosmetic Ingredient Review panel as of 2025.
- Common uses
- Water-resistant sunscreens, Long-wear makeup, Lip products
- Environmental note
- As a synthetic polymer, it is not readily biodegradable and may accumulate in the environment. Some regions are considering restrictions on non-biodegradable film-formers.
Good to know
- This ingredient is often listed near the end of an INCI list, meaning it's used in small amounts.
- It is different from microplastic beads used in scrubs; it forms a film rather than being a solid particle.
Common questions
What is Lithium Oxidized Polyethylene in beauty products?
This is a man-made ingredient that creates a thin, invisible film on your skin. It's mainly used to help sunscreen or makeup resist water and sweat, so they last longer. Think of it like a gentle, breathable plastic wrap that helps your product stay in place without feeling heavy.
What does Lithium Oxidized Polyethylene do in a beauty product?
When applied, the ingredient dries down to form a continuous, water-resistant film on the skin's surface. This film helps lock in other active ingredients and prevents them from being washed away by water or sweat. It also gives a smooth, silky feel to the product.
Is Lithium Oxidized Polyethylene safe for most people?
Generally considered safe for topical use at low concentrations, but long-term safety data is limited. It has low irritation and comedogenic potential based on available information.
Who should be careful with Lithium Oxidized Polyethylene?
Those with very sensitive or reactive 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.