What Is C11-15 Alketh-3 Stearate?
C11-15 Alketh-3 Stearate is an ester that joins a small group of synthetic fatty alcohols known as C11-15 Alketh-3 with stearic acid, a long-chain fatty acid most often taken from plant oils such as cocoa butter or palm. The C11-15 alcohols can be sourced from coconut or petroleum then reacted with a few units of ethylene oxide to make them more water friendly. When these ethoxylated alcohols are blended with stearic acid under heat and in the presence of a catalyst, the result is C11-15 Alketh-3 Stearate, a waxy solid that melts easily into creams and lotions.
The cosmetic world has relied on similar fatty esters since the 1970s to give products a smoother feel. Over time chemists refined the ratio of alcohol chain length to ethoxylation level, arriving at the C11-15 Alketh-3 profile that balances spreadability with a light skin feel. The ingredient’s earlier trade name was C11-15 Pareth-3 Stearate but was later updated to align with modern naming rules set by the Personal Care Products Council.
Because it mixes well with both oils and water, this ester shows up in a wide range of daily care items. You will find it in facial moisturizers, body lotions, sunscreens, foundations, makeup primers, rinse-off masks, creamy cleansers, hair conditioners and many anti-aging formulas that aim for a rich yet non-greasy finish.
C11-15 Alketh-3 Stearate’s Cosmetic Benefits/Uses
The main role of C11-15 Alketh-3 Stearate in skincare and beauty products is as an emollient, meaning it softens the skin surface and improves the texture of a formula. By filling in the tiny gaps between skin cells it leaves skin feeling silky and supple while helping other oily ingredients spread more evenly. Its semi-solid nature also boosts the body of a cream, giving formulators a way to create lush textures without heaviness.
Who Can Use C11-15 Alketh-3 Stearate
This emollient suits most skin types including dry, normal and combination because it softens without leaving a heavy greasy film. Those with very oily or easily congested skin may want to keep an eye on how their skin responds since richer fatty esters can occasionally feel too occlusive or lead to clogged pores in some individuals.
C11-15 Alketh-3 Stearate can be vegan friendly when the stearic acid portion is sourced from plants such as cocoa butter or palm oil. Because manufacturers may also use animal-derived stearic acid, strict vegans and vegetarians should check the origin with the brand.
The ingredient is considered low risk for women who are pregnant or breastfeeding. That said, this is not medical advice and anyone expecting or nursing should review all personal care products with a qualified healthcare provider to be sure they meet individual needs.
C11-15 Alketh-3 Stearate does not make skin more sensitive to sunlight, so there is no extra risk of photosensitivity. It is also fragrance free and generally non reactive alongside common actives like retinol or vitamin C.
Potential Side Effects/Adverse Reactions
Reactions to topical C11-15 Alketh-3 Stearate differ from person to person. The points below list potential side effects that could occur even though they are unlikely for most users when the ingredient is formulated and used correctly.
- Mild skin irritation – a small number of users may notice transient redness, itching or stinging
- Allergic contact dermatitis – rare sensitization can lead to persistent redness, swelling or rash
- Acne flare-ups – very oily or breakout prone skin might develop whiteheads or blackheads if the formula is too rich
- Eye irritation – temporary tearing or burning can occur if the product accidentally gets into the eyes
If you experience any of these issues stop using the product and consult a healthcare professional for guidance.
Comedogenic Rating
Rating: 2 out of 5. C11-15 Alketh-3 Stearate is a semi solid fatty ester, so it brings some richness, yet its short ethoxylated chain makes it more water friendly than heavier waxes. This lowers the chance of it lodging deep in pores, but a small risk of clogging still exists, especially in products that layer multiple rich oils or butters.
Most people prone to acne can usually tolerate it in lightweight formulas, though those with very reactive or severely congested skin may prefer to avoid it.
Keep in mind that the final comedogenic impact depends on the full recipe and the percentage used, not just the presence of this single ingredient.
Summary
C11-15 Alketh-3 Stearate works primarily as an emollient that softens skin, smooths texture and helps other oils glide across the surface. Its blend of a short ethoxylated alcohol with stearic acid lets it melt into both water and oil phases, giving creams a plush feel without an oily residue.
While not a headline ingredient, it is a steady performer found in many moisturizers, sunscreens, foundations and conditioners where a silky touch is desired.
Safety tests and decades of use show it is generally low risk for irritation or sensitization. Still, skin can be unpredictable, so doing a small patch test with any new product that contains C11-15 Alketh-3 Stearate is always a smart move.