Ingredient review
Bis-Hydroxypropyl Dimethicone/SMDI Copolymer
INCI: BIS-HYDROXYPROPYL DIMETHICONE/SMDI COPOLYMER
A silicone polymer that helps products stay put, resist water, and feel smooth, with a good safety profile for most skin types.
In plain English
This is a man-made silicone ingredient that forms a thin, flexible film on your skin. It helps makeup and sunscreen last longer, resist water and sweat, and feel silky without being heavy or sticky. It's similar to other silicones used in cosmetics but is designed to be more durable and comfortable.
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
Bis-Hydroxypropyl Dimethicone/SMDI Copolymer 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 Bis-Hydroxypropyl Dimethicone/SMDI Copolymer.
- 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 copolymer made from silicone (dimethicone) and a special isocyanate (SMDI). It is a film-forming agent that creates a flexible, breathable layer on the skin or hair.
How it works
When applied, the copolymer dries to form a thin, invisible film that adheres to the skin. This film helps lock in other ingredients, prevents makeup from smudging or fading, and provides a smooth, velvety feel. It also repels water, making it ideal for waterproof and long-wear formulas.
Pros
Long-lasting wear
Creates a durable film that helps makeup and sunscreen stay put for hours, even in humidity or water.
Smooth texture
Gives a silky, non-greasy feel that makes products glide on easily and feel lightweight.
Cons and cautions
Potential tightness
The film can feel slightly tight or drying on very dry or sensitive skin, especially if used in high concentrations.
Environmental persistence
As a silicone-based polymer, it is not readily biodegradable and may accumulate in the environment.
Best for
- People who want long-lasting makeup or sunscreen
- Those with oily or combination skin who prefer a matte finish
Use caution if
- Individuals with very dry or dehydrated skin who may find film-formers uncomfortable
Usage tips
Safety summary
Bis-Hydroxypropyl Dimethicone/SMDI Copolymer is considered safe for use in cosmetics at typical concentrations. It has low irritation and comedogenic potential, making it suitable for most skin types. However, as with any film-former, individuals with very dry or sensitive skin should patch test first.
Research notes
Research on this specific copolymer is limited, but it is structurally similar to other well-studied silicone film-formers. Safety assessments by the Cosmetic Ingredient Review (CIR) panel have found silicone polymers of this type to be safe for topical use. No significant toxicity or sensitization has been reported.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics globally, including by the US FDA and EU CosIng database, with no known restrictions at typical concentrations.
- Common uses
- Long-wear foundations, Sunscreens, Waterproof mascaras, Primers
- Environmental note
- Silicone polymers like this one are not biodegradable and can persist in water systems. Some manufacturers are working on more eco-friendly alternatives.
Good to know
- This ingredient is often used in combination with other silicones to balance feel and performance.
- It is considered safe by major cosmetic safety panels when used as intended.
Common questions
What is Bis-Hydroxypropyl Dimethicone/SMDI Copolymer in beauty products?
This is a man-made silicone ingredient that forms a thin, flexible film on your skin. It helps makeup and sunscreen last longer, resist water and sweat, and feel silky without being heavy or sticky. It's similar to other silicones used in cosmetics but is designed to be more durable and comfortable.
What does Bis-Hydroxypropyl Dimethicone/SMDI Copolymer do in a beauty product?
When applied, the copolymer dries to form a thin, invisible film that adheres to the skin. This film helps lock in other ingredients, prevents makeup from smudging or fading, and provides a smooth, velvety feel. It also repels water, making it ideal for waterproof and long-wear formulas.
Is Bis-Hydroxypropyl Dimethicone/SMDI Copolymer safe for most people?
Bis-Hydroxypropyl Dimethicone/SMDI Copolymer is considered safe for use in cosmetics at typical concentrations. It has low irritation and comedogenic potential, making it suitable for most skin types. However, as with any film-former, individuals with very dry or sensitive skin should patch test first.
Who should be careful with Bis-Hydroxypropyl Dimethicone/SMDI Copolymer?
Individuals with very dry or dehydrated skin 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.