Ingredient review
Undecanoic Acid Dimethicones
INCI: UNDECANOIC ACID DIMETHICONES
A gentle silicone derivative that helps products spread smoothly and resist water, but may not suit those avoiding all silicones.
In plain English
Undecanoic Acid Dimethicones is a hybrid ingredient made by attaching a fatty acid (undecanoic acid) to a silicone chain. In plain terms, it is a silicone that has been modified to be more compatible with skin and water-based formulas. It works by forming a thin, breathable film on the skin or hair that feels silky and helps lock in moisture without a heavy or greasy feel. It also helps other ingredients spread evenly and can improve the water resistance of sunscreens and makeup.
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
- semi synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Undecanoic Acid Dimethicones 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 Undecanoic Acid Dimethicones.
- 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 semi-synthetic silicone polymer modified with undecanoic acid, a fatty acid naturally found in some plants and also produced synthetically. It belongs to the dimethicone family but has improved compatibility with water and other polar ingredients.
How it works
When applied, it dries down to a flexible, non-sticky film that sits on the surface of the skin or hair. This film reduces water loss (transepidermal water loss, or TEWL — the amount of moisture that evaporates from your skin) and provides a smooth, velvety feel. It also helps other ingredients like pigments or UV filters spread more evenly and stay in place longer.
Pros
Lightweight feel
Unlike some heavier oils or waxes, this silicone derivative leaves a silky, non-sticky finish that works well under makeup or alone.
Water resistance
It helps sunscreens and long-wear products stay effective longer during swimming, sweating, or humid conditions.
Cons and cautions
Silicone avoidance
If you prefer silicone-free routines, this ingredient is not an option — it is a modified silicone and will appear on labels as such.
Removal difficulty
Its film-forming nature means it may not wash off completely with a gentle cleanser alone, potentially requiring an oil-based cleanser or double cleansing.
Best for
- People looking for a lightweight, non-greasy moisturizer or primer
- Those who want longer-lasting makeup or sunscreen that resists sweat and water
Use caution if
- Individuals who strictly avoid silicones in their skincare routine
Usage tips
Safety summary
Undecanoic Acid Dimethicones is considered safe for use in cosmetics at typical concentrations. It has low irritation and comedogenic potential, making it suitable for most skin types, including sensitive skin. However, as with any ingredient, patch testing is recommended for those with known sensitivities.
Research notes
Safety assessments of silicone derivatives, including dimethicone copolyols and modified dimethicones, have been conducted by the Cosmetic Ingredient Review (CIR) panel, which found them safe as used. Specific studies on Undecanoic Acid Dimethicones are limited, but its chemical structure is similar to other well-studied silicone film formers.
Common label clues
- Typical concentration
- 0.5% to 5% in leave-on products; up to 10% in rinse-off products
- Regulatory status
- Approved for use in cosmetics in the US, EU, and other major markets. No specific restrictions beyond general cosmetic safety requirements.
- Common uses
- Moisturizers, Sunscreens, Makeup primers, Hair serums, Color cosmetics
- Environmental note
- Silicones, including modified ones, can persist in the environment. Some formulations may be designed to be biodegradable, but check product-specific claims.
Good to know
- Undecanoic acid is a medium-chain fatty acid that occurs naturally in some plants, but the version used here is typically synthesized for purity and consistency.
- This ingredient is considered non-comedogenic in most formulations, but individual reactions can vary.
Common questions
What is Undecanoic Acid Dimethicones in beauty products?
Undecanoic Acid Dimethicones is a hybrid ingredient made by attaching a fatty acid (undecanoic acid) to a silicone chain. In plain terms, it is a silicone that has been modified to be more compatible with skin and water-based formulas. It works by forming a thin, breathable film on the skin or hair that feels silky and helps lock in moisture without a heavy or greasy feel. It also helps other ingredients spread evenly and can improve the water resistance of sunscreens and makeup.
What does Undecanoic Acid Dimethicones do in a beauty product?
When applied, it dries down to a flexible, non-sticky film that sits on the surface of the skin or hair. This film reduces water loss (transepidermal water loss, or TEWL — the amount of moisture that evaporates from your skin) and provides a smooth, velvety feel. It also helps other ingredients like pigments or UV filters spread more evenly and stay in place longer.
Is Undecanoic Acid Dimethicones safe for most people?
Undecanoic Acid Dimethicones is considered safe for use in cosmetics at typical concentrations. It has low irritation and comedogenic potential, making it suitable for most skin types, including sensitive skin. However, as with any ingredient, patch testing is recommended for those with known sensitivities.
Who should be careful with Undecanoic Acid Dimethicones?
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.