Decyl oleate is an ingredient used to formulate a variety of cosmetics and personal care products, functioning as an emollient and skin-conditioning agent. It is comedogenic and should be avoided by those with acne prone skin.
Decyl oleate is an ester of decyl alcohol and oleic acid. Decyl alcohol, also known as 1-decanol, is a straight chain fatty alcohol with ten carbon atoms. Oleic acid is a monounsaturated omega-9 fatty acid that occurs naturally in various animal and vegetable fats and oils, for instance, olive oil. These two substances can be reacted together to form decyl oleate. Decyl oleate is a clear, yellow liquid that is soluble in most hydrophobic solvents such as silicones, esters, mineral oils, vegetable oils and mineral spirits.
In cosmetics and personal care products, decyl oleate functions as an emollient and skin-conditioning agent. Decyl oleate can be found in products such as facial moisturizers, body moisturizers, anti-aging treatments, sunscreens, makeup, makeup removers, hair conditioners, and aftershave products.
As an emollient, decyl oleate works to soften and soothe the skin by acting as a lubricant. Decyl oleate can be classified as an occlusive emollient because it forms a thin film on the skin that is neither greasy nor tacky. The film also helps to prevent evaporation of the skin’s natural moisture. Over time, this increases skin hydration by causing buildup of water in the stratum corneum (the uppermost layer of skin).
While all skin types can benefit from emollients like decyl oleate, emollients are especially helpful for those who have dry, rough, and/or flaky skin. Emollients can alleviate these symptoms, leaving the skin looking and feeling soft and smooth. In addition, emollients can benefit those that suffer from conditions such as eczema, psoriasis, or other inflammatory skin conditions.
Decyl oleate can also be found in hair conditioners and other hair care products because of its emollient properties. Similar to how emollients work on the skin, an emollient for hair should easily form a smooth, even film on the surface of the hair. This film helps to seal in moisture and soften the hair. Emollients act as lubricants and provide increased slip between adjacent hair strands, which makes detangling much easier. Hair emollients also smooth and flatten the cuticle surface, which adds shine and gloss to the hair.
One drawback of decyl oleate is that it is highly comedogenic. Comedogenic means that an ingredient tends to cause blackheads by blocking the pores of the skin. Even if a single ingredient, such as decyl oleate, in a skin care or cosmetic product is comedogenic, the product as a whole is considered to be comedogenic. Decyl oleate is very likely to cause breakouts for those with acne prone skin. If your skin does not break out easily, it is still recommended to use caution with facial products containing this ingredient.
The safety of decyl oleate has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. Clinical studies indicate that decyl oleate possesses low acute oral toxicity. Single application dermal and eye studies have shown that a 100% concentration of decyl oleate produces little or no irritation. Decyl oleate was also not found to be a skin sensitizer. After evaluating all scientific data, the CIR Expert Panel concluded that decyl oleate was safe at the reported use concentrations in cosmetics and personal care products.
The safety of decyl oleate has also been assessed by EWG’s Skin Deep Cosmetic Database. It is rated as a 1 on a scale of 1 to 10, with 1 being the lowest risk to health and 10 being the highest. However, the Database does indicate that there is limited data available regarding decyl oleate.
References: Making Cosmetics “Decyl Oleate”, Truth In Aging “Decyl Oleate”, Cosmetics Info “Decyl Oleate”, EWG’s Skin Deep Cosmetic Database “Decyl Oleate”, Acne Mantra “Is Decyl Oleate Comedogenic?”