Ingredient review
Polysilicone-21
INCI: POLYSILICONE-21
Polysilicone-21 is a gentle, non-comedogenic film former that helps products spread smoothly and resist water without feeling heavy.
In plain English
Polysilicone-21 is a type of silicone that forms a thin, flexible film on your skin. This film helps other ingredients stay in place, makes the product feel silky, and can improve water resistance in sunscreens or long-wear makeup. It's designed to be lightweight and breathable, so it doesn't clog pores or feel greasy.
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
Polysilicone-21 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 Polysilicone-21.
- 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
Polysilicone-21 is a synthetic silicone polymer engineered to create a protective, water-resistant film on the skin. It belongs to the family of film-forming silicones, which are valued for their smooth application and durability.
How it works
When applied, Polysilicone-21 spreads into a thin, even layer that dries to form a flexible film. This film helps lock in other active ingredients, reduces water loss from the skin, and provides a smooth base for makeup. It also helps sunscreens stay effective longer by resisting sweat and water.
Pros
Lightweight feel
Polysilicone-21 creates a silky, non-greasy film that doesn't weigh down the skin, making it ideal for daily wear.
Boosts water resistance
It helps sunscreens and makeup stay effective longer by forming a barrier that resists sweat and water.
Cons and cautions
Not water-soluble
Products with Polysilicone-21 may require a gentle cleanser or double cleansing to fully remove, especially if layered.
Silicone concerns
Some users avoid silicones due to environmental persistence or personal preference, even though this ingredient is generally safe.
Best for
- People who want long-wearing makeup or water-resistant sunscreen
- Those with normal to oily skin looking for a non-greasy finish
Use caution if
- Individuals who strictly avoid silicones in their skincare routine
Usage tips
Safety summary
Polysilicone-21 is considered safe for use in cosmetics at typical concentrations. It has low irritation and comedogenic potential, making it suitable for most skin types. As with all silicones, some individuals may choose to avoid it for environmental reasons.
Research notes
Research on Polysilicone-21 is limited but consistent with other film-forming silicones. It is recognized as safe by cosmetic ingredient review panels and is widely used in commercial products. No significant safety concerns have been reported in published literature.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics in the EU, US, and many other regions. It is not classified as a hazardous substance under standard cosmetic regulations.
- Common uses
- Moisturizers, Sunscreens, Primers, Long-wear makeup
- Environmental note
- Silicones like Polysilicone-21 are generally not biodegradable and may accumulate in the environment. However, they are used in low concentrations and are not known to be toxic to aquatic life.
Good to know
- Polysilicone-21 is considered non-comedogenic, meaning it's unlikely to clog pores.
- It is often used in combination with other silicones to fine-tune texture and feel.
Common questions
What is Polysilicone-21 in beauty products?
Polysilicone-21 is a type of silicone that forms a thin, flexible film on your skin. This film helps other ingredients stay in place, makes the product feel silky, and can improve water resistance in sunscreens or long-wear makeup. It's designed to be lightweight and breathable, so it doesn't clog pores or feel greasy.
What does Polysilicone-21 do in a beauty product?
When applied, Polysilicone-21 spreads into a thin, even layer that dries to form a flexible film. This film helps lock in other active ingredients, reduces water loss from the skin, and provides a smooth base for makeup. It also helps sunscreens stay effective longer by resisting sweat and water.
Is Polysilicone-21 safe for most people?
Polysilicone-21 is considered safe for use in cosmetics at typical concentrations. It has low irritation and comedogenic potential, making it suitable for most skin types. As with all silicones, some individuals may choose to avoid it for environmental reasons.
Who should be careful with Polysilicone-21?
Individuals who strictly avoid silicones in their skincare routine
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.