Ingredient review
Methoxycinnamidopropyl Polysilsesquioxane
INCI: METHOXYCINNAMIDOPROPYL POLYSILSESQUIOXANE
A silicone-based UV filter that also improves product spreadability and water resistance, but its use is limited outside Asia.
In plain English
This ingredient is a special type of silicone that has a UV-absorbing molecule attached to it. In a sunscreen or makeup product, it helps block UV rays while also making the product feel silky, spread easily, and resist water. It is often used in Asian sunscreens to create a lightweight, non-greasy finish.
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
Methoxycinnamidopropyl Polysilsesquioxane 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 Methoxycinnamidopropyl Polysilsesquioxane.
- 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 hybrid molecule that combines a UV-absorbing cinnamate group with a polysilsesquioxane silicone backbone. It is a solid powder at room temperature and is designed to be both a UV filter and a film-forming agent.
How it works
The cinnamate part absorbs UVB rays (and some UVA) and converts them into harmless heat. The silicone backbone helps the ingredient form an even, flexible film on the skin, which improves water resistance and gives a smooth, silky feel. It also helps disperse other sunscreen ingredients evenly.
Pros
Lightweight feel
Unlike some traditional UV filters that can feel heavy or greasy, this silicone-based ingredient gives a silky, almost powdery finish that many people find pleasant.
Boosts water resistance
Its film-forming ability helps sunscreen stay on the skin longer during swimming or sweating, reducing the need for frequent reapplication.
Cons and cautions
Limited regulatory approval
This ingredient is not approved as a UV filter in the United States or European Union, so you will only find it in sunscreens sold in Asia and a few other regions.
Not broad-spectrum alone
It primarily absorbs UVB rays and offers limited UVA protection, so it is almost always combined with other filters for complete sun protection.
Best for
- People who prefer lightweight, non-greasy sunscreens
- Those looking for water-resistant sun protection
Use caution if
- Anyone who strictly avoids silicones in their skincare
Usage tips
Safety summary
Generally considered safe for topical use in cosmetics at typical concentrations. Skin irritation and allergy are rare. However, long-term safety data is less extensive than for some traditional UV filters, and it is not approved in all regions.
Research notes
Studies show it is an effective UVB filter with good photostability and water resistance. Most safety data comes from manufacturer-sponsored studies and regulatory submissions in Asia. Independent peer-reviewed research is limited.
Common label clues
- Typical concentration
- 1% to 10%
- Regulatory status
- Approved as a UV filter in Japan, South Korea, and other Asian countries. Not approved for use as a sunscreen active in the US (FDA) or EU (CosIng).
- Common uses
- Sunscreens, Tinted moisturizers, Foundations, Primers
- Environmental note
- As a silicone-based compound, it may be persistent in the environment. However, its environmental impact is less studied than that of some older UV filters like oxybenzone.
Good to know
- This ingredient is often listed under trade names like Parsol SLX or Polysilicone-15 in ingredient lists.
- It is a powder, so it can help mattify the skin and reduce shine in sunscreens.
Common questions
What is Methoxycinnamidopropyl Polysilsesquioxane in beauty products?
This ingredient is a special type of silicone that has a UV-absorbing molecule attached to it. In a sunscreen or makeup product, it helps block UV rays while also making the product feel silky, spread easily, and resist water. It is often used in Asian sunscreens to create a lightweight, non-greasy finish.
What does Methoxycinnamidopropyl Polysilsesquioxane do in a beauty product?
The cinnamate part absorbs UVB rays (and some UVA) and converts them into harmless heat. The silicone backbone helps the ingredient form an even, flexible film on the skin, which improves water resistance and gives a smooth, silky feel. It also helps disperse other sunscreen ingredients evenly.
Is Methoxycinnamidopropyl Polysilsesquioxane safe for most people?
Generally considered safe for topical use in cosmetics at typical concentrations. Skin irritation and allergy are rare. However, long-term safety data is less extensive than for some traditional UV filters, and it is not approved in all regions.
Who should be careful with Methoxycinnamidopropyl Polysilsesquioxane?
Anyone who strictly avoids silicones in their skincare
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.