Ingredient review
Trimethylsiloxysilicate/Dimethicone Crosspolymer
INCI: TRIMETHYLSILOXYSILICATE/DIMETHICONE CROSSPOLYMER
A silicone film-former that helps makeup last longer and boosts water resistance without feeling heavy.
In plain English
This is a synthetic silicone ingredient that forms a thin, flexible film on your skin or hair. It helps makeup stay put longer, makes sunscreens more water-resistant, and gives a smooth, silky feel. It’s not absorbed into the skin—it sits on top and creates a protective layer.
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
Trimethylsiloxysilicate/Dimethicone 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 Trimethylsiloxysilicate/Dimethicone 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 crosslinked silicone polymer made by combining trimethylsiloxysilicate (a film-forming resin) with dimethicone (a common silicone oil). The crosslinking creates a flexible, breathable film that is more durable than either ingredient alone.
How it works
When applied, the polymer spreads into a thin, even film that dries down to a flexible, water-resistant barrier. This film helps lock in other ingredients, reduces water loss from the skin, and prevents makeup from smudging or fading. On hair, it smooths the cuticle and adds shine without greasiness.
Pros
Boosts wear time
Helps foundation and sunscreen stay put for hours, even in humidity or water exposure.
Lightweight feel
Unlike some waxes or oils, this polymer forms a thin, flexible film that doesn't feel heavy or greasy.
Cons and cautions
Removal can be tricky
Because it's water-resistant, you may need an oil-based cleanser or double cleanse to fully remove it, especially from hair.
Environmental persistence
As a silicone-based polymer, it is not biodegradable and can accumulate in the environment.
Best for
- Anyone wanting long-lasting makeup or water-resistant sunscreen
- People with oily skin who prefer a matte, smooth finish
Use caution if
- Those who prefer silicone-free or fully biodegradable formulas
- Individuals with very dry skin who may find film-formers too occlusive
Usage tips
Safety summary
Trimethylsiloxysilicate/Dimethicone Crosspolymer is considered safe for topical use at typical cosmetic concentrations. It is not absorbed into the skin and has very low irritation and comedogenic potential. The main concern is environmental persistence.
Research notes
Safety assessments by the Cosmetic Ingredient Review (CIR) panel have concluded that dimethicone crosspolymers are safe as used. Studies show they are non-irritating, non-sensitizing, and do not penetrate the skin barrier. Environmental data is limited but indicates poor biodegradability.
Common label clues
- Typical concentration
- 1–10% in leave-on products; higher in waterproof formulas
- Regulatory status
- Approved for use in cosmetics in the US (FDA), EU (CosIng), and other major markets. No concentration restrictions for leave-on products.
- Common uses
- Long-wear foundations, Sunscreens, Primers, Hair serums, Water-resistant formulas
- Environmental note
- As a silicone-based polymer, it is not biodegradable and may contribute to microplastic pollution. Some manufacturers are exploring bio-based alternatives.
Good to know
- This ingredient is often used in 'transfer-proof' or '24-hour' makeup formulas.
- It is considered safe for use in cosmetics by major regulatory bodies at typical concentrations.
Common questions
What is Trimethylsiloxysilicate/Dimethicone Crosspolymer in beauty products?
This is a synthetic silicone ingredient that forms a thin, flexible film on your skin or hair. It helps makeup stay put longer, makes sunscreens more water-resistant, and gives a smooth, silky feel. It’s not absorbed into the skin—it sits on top and creates a protective layer.
What does Trimethylsiloxysilicate/Dimethicone Crosspolymer do in a beauty product?
When applied, the polymer spreads into a thin, even film that dries down to a flexible, water-resistant barrier. This film helps lock in other ingredients, reduces water loss from the skin, and prevents makeup from smudging or fading. On hair, it smooths the cuticle and adds shine without greasiness.
Is Trimethylsiloxysilicate/Dimethicone Crosspolymer safe for most people?
Trimethylsiloxysilicate/Dimethicone Crosspolymer is considered safe for topical use at typical cosmetic concentrations. It is not absorbed into the skin and has very low irritation and comedogenic potential. The main concern is environmental persistence.
Who should be careful with Trimethylsiloxysilicate/Dimethicone Crosspolymer?
Those who prefer silicone-free or fully biodegradable formulas Individuals with very dry skin who may find film-formers too occlusive
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.