Ingredient review

Polysilicone-18

INCI: Polysilicone-18

Polysilicone-18 is a gentle silicone film-former that helps products stay put and resist water, but it may feel heavy on oily or acne-prone skin.

beautyskincarefilm-former

In plain English

Polysilicone-18 is a type of silicone that forms a thin, flexible film on your skin. Think of it like a very lightweight, breathable raincoat that helps your makeup or sunscreen stay in place longer and resist sweat or water. It's often used in products that need to last all day or provide water resistance, like sunscreens and primers. Because it's a silicone, it can give a smooth, silky feel, but it might feel a bit heavy or slippery for some people, especially those with very oily skin.

Review score

Safety, usefulness, and evidence

4.0Good
4.0/ 5

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
How reviews are scored

Quick decision guide

Useful, but context matters

Polysilicone-18 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.

  1. Step 1Start with the score, then check the irritation and clogging risk before judging Polysilicone-18.
  2. Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
  3. 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

low

Less likely to sting, burn, or bother most users, though sensitive skin can still react.

Clogging risk

low

Less likely to feel heavy or contribute to clogged pores for most skin types.

Evidence level

moderate

There is useful support, but formula details and claim strength still matter.

What it is

Polysilicone-18 is a synthetic silicone polymer. It's a large molecule made of repeating silicone units, designed to form a flexible, water-resistant film on the skin or hair.

How it works

When applied, the silicone molecules link together to create a thin, breathable film. This film helps lock in other ingredients, prevents water from evaporating too quickly, and makes the product more resistant to water and sweat. It also helps pigments (like in foundation) stay in place and not smudge.

Pros

Excellent water resistance

Polysilicone-18 helps sunscreens and makeup stay effective even when you sweat or swim, so you don't have to reapply as often.

Smooth, silky texture

It gives products a luxurious, non-greasy feel that glides on easily and helps makeup apply evenly.

Cons and cautions

Can feel heavy on oily skin

If you have very oily skin, the film formed by Polysilicone-18 might feel slippery or like a layer that doesn't fully absorb.

Requires double cleansing

Because it's water-resistant, you may need an oil-based cleanser or micellar water to remove it completely, which adds a step to your routine.

Best for

  • People who need long-wearing makeup or water-resistant sunscreen
  • Those with normal to dry skin looking for a smooth, protective layer

Use caution if

  • Individuals with very oily or acne-prone skin who find silicones heavy or pore-clogging
  • Those who prefer fully biodegradable or natural ingredients

Usage tips

Use an oil-based cleanser or micellar water first to break down the silicone film, then follow with your regular water-based cleanser.
If you have oily skin, try using products with Polysilicone-18 only on areas where you need extra staying power, like the T-zone.

Safety summary

Polysilicone-18 is considered safe for topical use in cosmetics. It has low irritation and comedogenic potential, meaning it's unlikely to clog pores or cause allergic reactions for most people. However, its environmental persistence is a concern.

Research notes

Research on Polysilicone-18 specifically is limited, but studies on similar silicone film-formers show they are effective at improving water resistance and wear time without significant skin irritation. Most safety data comes from broader reviews of silicone polymers.

Common label clues

Typical concentration
0.5% to 5%
Regulatory status
Approved for use in cosmetics in the US, EU, and many other regions. The Cosmetic Ingredient Review (CIR) panel has reviewed similar silicones and found them safe at typical use levels.
Common uses
Sunscreens, Primers, Long-wear foundations, Water-resistant moisturizers
Environmental note
Like many silicones, Polysilicone-18 is not readily biodegradable and may persist in the environment. Some manufacturers are working on more eco-friendly alternatives.

Good to know

  • Polysilicone-18 is often combined with other silicones or film-formers to boost water resistance without making the product too thick.
  • It is considered safe for use in cosmetics by major regulatory bodies, but its environmental impact is a growing concern.

Common questions

What is Polysilicone-18 in beauty products?

Polysilicone-18 is a type of silicone that forms a thin, flexible film on your skin. Think of it like a very lightweight, breathable raincoat that helps your makeup or sunscreen stay in place longer and resist sweat or water. It's often used in products that need to last all day or provide water resistance, like sunscreens and primers. Because it's a silicone, it can give a smooth, silky feel, but it might feel a bit heavy or slippery for some people, especially those with very oily skin.

What does Polysilicone-18 do in a beauty product?

When applied, the silicone molecules link together to create a thin, breathable film. This film helps lock in other ingredients, prevents water from evaporating too quickly, and makes the product more resistant to water and sweat. It also helps pigments (like in foundation) stay in place and not smudge.

Is Polysilicone-18 safe for most people?

Polysilicone-18 is considered safe for topical use in cosmetics. It has low irritation and comedogenic potential, meaning it's unlikely to clog pores or cause allergic reactions for most people. However, its environmental persistence is a concern.

Who should be careful with Polysilicone-18?

Individuals with very oily or acne-prone skin who find silicones heavy or pore-clogging Those who prefer fully biodegradable or natural ingredients

Research sources

Cosmetic Ingredient Review (CIR) - Safety of SiliconesOpenPubMed - Silicone Polymers in CosmeticsOpenEnvironmental Working Group (EWG) - Polysilicone-18Open

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.