Ingredient review
HDI/PEI-45/SMDI Crosspolymer
INCI: HDI/PEI-45/SMDI CROSSPOLYMER
A synthetic polymer that helps makeup last longer and feel smoother, but offers no skincare benefit.
In plain English
This is a man-made ingredient that forms a thin, flexible film on your skin. It's used in products like foundation and concealer to help them stay put longer, resist smudging, and feel silky. Think of it as a gentle glue that holds the product together on your face without clogging pores or causing irritation for most people.
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
HDI/PEI-45/SMDI Crosspolymer 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 HDI/PEI-45/SMDI Crosspolymer.
- 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 crosspolymer created by reacting three chemical building blocks (HDI, PEI-45, and SMDI). It belongs to the polyurethane family and is designed to create a flexible, water-resistant film on the skin.
How it works
When applied, the polymer molecules link together to form a thin, invisible mesh over the skin. This mesh locks in pigments and other ingredients, making the product more resistant to sweat, water, and rubbing. It also helps the product spread evenly and gives a smooth, silky feel.
Pros
Boosts makeup longevity
Helps foundation and concealer stay in place for hours without fading or creasing, reducing the need for touch-ups.
Silky, non-greasy feel
Gives products a smooth, velvety texture that glides on easily and doesn't feel sticky or heavy on the skin.
Cons and cautions
Purely cosmetic, no skin benefit
This ingredient only improves product performance; it doesn't hydrate, soothe, or treat any skin concerns.
May feel drying for some
The film it creates can occasionally feel tight or dry on very dry or sensitive skin, especially if used in high concentrations.
Best for
- Anyone wanting long-lasting makeup
- People with normal to oily skin who need extra staying power
Use caution if
- Those who prefer only natural or plant-based ingredients
- Individuals with extremely dry or compromised skin barriers who may find film-formers uncomfortable
Usage tips
Safety summary
HDI/PEI-45/SMDI Crosspolymer is considered safe for use in cosmetics. It has a low risk of skin irritation or allergic reactions for most people. It does not clog pores and is not absorbed into the skin. As with any ingredient, patch test if you have very sensitive skin.
Research notes
Safety assessments by cosmetic ingredient review panels and regulatory agencies have not raised significant concerns about this polymer at typical use levels. Most evidence comes from manufacturer safety data and general polymer toxicology, not 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. No specific concentration restrictions are common, but it is typically used at low levels.
- Common uses
- Foundations, Concealers, Long-wear makeup, Sunscreens
- Environmental note
- As a synthetic polymer, it is not biodegradable. However, it is used in very small amounts per product, and its environmental impact is considered low compared to microplastics.
Good to know
- This ingredient is often found in 'transfer-proof' or '24-hour wear' makeup formulas.
- It is considered safe for use in cosmetics by major regulatory bodies when used as intended.
Common questions
What is HDI/PEI-45/SMDI Crosspolymer in beauty products?
This is a man-made ingredient that forms a thin, flexible film on your skin. It's used in products like foundation and concealer to help them stay put longer, resist smudging, and feel silky. Think of it as a gentle glue that holds the product together on your face without clogging pores or causing irritation for most people.
What does HDI/PEI-45/SMDI Crosspolymer do in a beauty product?
When applied, the polymer molecules link together to form a thin, invisible mesh over the skin. This mesh locks in pigments and other ingredients, making the product more resistant to sweat, water, and rubbing. It also helps the product spread evenly and gives a smooth, silky feel.
Is HDI/PEI-45/SMDI Crosspolymer safe for most people?
HDI/PEI-45/SMDI Crosspolymer is considered safe for use in cosmetics. It has a low risk of skin irritation or allergic reactions for most people. It does not clog pores and is not absorbed into the skin. As with any ingredient, patch test if you have very sensitive skin.
Who should be careful with HDI/PEI-45/SMDI Crosspolymer?
Those who prefer only natural or plant-based ingredients Individuals with extremely dry or compromised skin barriers who may 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.