Ingredient review

Dimethiconol/Silsesquioxane Copolymer

INCI: Dimethiconol/Silsesquioxane Copolymer

A gentle silicone film-former that improves wear time and water resistance without feeling heavy or greasy.

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In plain English

This is a type of silicone that dries down to a flexible, invisible film on your skin or hair. It helps makeup last longer, makes sunscreen more water-resistant, and gives hair a smooth, shiny finish. Unlike some older silicones, it doesn't feel slippery or heavy.

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

Dimethiconol/Silsesquioxane 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.

  1. Step 1Start with the score, then check the irritation and clogging risk before judging Dimethiconol/Silsesquioxane Copolymer.
  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

A synthetic silicone polymer made by combining dimethiconol (a silicone fluid) with silsesquioxane (a silicone resin). The result is a hybrid material that forms a breathable, flexible film.

How it works

When applied, the copolymer's molecules link together as the solvent (often water or a volatile silicone) evaporates, creating a thin, even film. This film adheres to the skin or hair surface, providing a smooth base for makeup, locking in moisture, and repelling water.

Pros

Long-wear performance

Creates a flexible film that helps makeup and sunscreen stay put for hours, even in humid conditions.

Lightweight feel

Unlike some film-formers, this copolymer dries to a soft, non-tacky finish that doesn't feel heavy or sticky on the skin.

Cons and cautions

May feel occlusive for oily skin

The film can trap oil and sweat, which might feel uncomfortable for those with very oily skin, especially in hot weather.

Not biodegradable

As a synthetic silicone, it does not break down easily in the environment, which is a concern for eco-conscious consumers.

Best for

  • Anyone looking for long-lasting makeup or water-resistant sunscreen
  • People with dry or normal skin who want a smooth, non-greasy finish

Use caution if

  • Those who strictly avoid silicones in their skincare routine

Usage tips

Apply to clean, dry skin before makeup for best adhesion and longevity.
Use a gentle oil-based cleanser or micellar water to remove products containing this ingredient thoroughly.

Safety summary

Generally recognized as safe for cosmetic use. Low irritation and comedogenic risk. No significant safety concerns reported in routine use.

Research notes

Limited independent research on this specific copolymer, but silicones as a class have been extensively reviewed and are considered safe. The CIR panel has given it a favorable safety assessment.

Common label clues

Typical concentration
1% to 10%
Regulatory status
Approved for use in cosmetics globally. The Cosmetic Ingredient Review (CIR) panel has evaluated it and found it safe for use in concentrations up to 10%.
Common uses
Long-wear foundations, Sunscreens, Primers, Hair serums, Water-resistant products
Environmental note
As a silicone, it is not biodegradable and may accumulate in aquatic environments. Some brands are moving toward biodegradable alternatives.

Good to know

  • This ingredient is often used in combination with other silicones to balance texture and feel.
  • It is considered safe by major regulatory bodies including the Cosmetic Ingredient Review (CIR) panel.

Common questions

What is Dimethiconol/Silsesquioxane Copolymer in beauty products?

This is a type of silicone that dries down to a flexible, invisible film on your skin or hair. It helps makeup last longer, makes sunscreen more water-resistant, and gives hair a smooth, shiny finish. Unlike some older silicones, it doesn't feel slippery or heavy.

What does Dimethiconol/Silsesquioxane Copolymer do in a beauty product?

When applied, the copolymer's molecules link together as the solvent (often water or a volatile silicone) evaporates, creating a thin, even film. This film adheres to the skin or hair surface, providing a smooth base for makeup, locking in moisture, and repelling water.

Is Dimethiconol/Silsesquioxane Copolymer safe for most people?

Generally recognized as safe for cosmetic use. Low irritation and comedogenic risk. No significant safety concerns reported in routine use.

Who should be careful with Dimethiconol/Silsesquioxane Copolymer?

Those who strictly avoid silicones in their skincare routine

Research sources

Cosmetic Ingredient Review (CIR) Safety AssessmentOpenPubMed - Silicones in CosmeticsOpenEnvironmental Working Group (EWG) - Dimethiconol/Silsesquioxane CopolymerOpen

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.