Caprylyl glycol is a skin conditioning agent that adds moisturization and wetting properties to many cosmetics and personal care products, as well as functions as a preservative booster.
Caprylyl glycol (1,2-octanediol) is an alcohol derived from caprylic acid, an eight carbon saturated fatty acid found in the milk of some mammals, as well as palm and coconut oils. It is a colorless liquid with a mild odor. Caprylic acid is classified as a medium chain triglyceride (MCT) with potent antibacterial, antifungal, and anti-inflammatory properties, according to Healthline.
Caprylyl glycol can also be synthetically produced. Commercial production of caprylyl glycol typically starts with the synthesis of ethylene glycol, the simplest of the 1,2-glycols. This usually happens by thermal oxidation of ethylene oxide with water. The commercial production of 1,2-glycols, including caprylyl glycol, are commonly made either via catalytic oxidation of the corresponding alkene oxide, or reduction of the corresponding 2-hydroxy acid.
Glycols are used in cosmetics and personal care products because of their neutral (slightly sweet) scent, neutral color, their excellent chemical stability, and their long shelf-life. Specifically, caprylyl glycol functions as a skin conditioning agent and a humectant moisturizer.
Caprylyl glycol also functions as a stabilizer and has been shown to increase the antimicrobial activity of other preservatives. The antimicrobial properties of this ingredient are most likely due to the antimicrobial properties of caprylic acid. Thus, adding caprylyl glycol to a product can help to prevent other ingredients from spoiling and extend the shelf life of the product. This ingredient is often used in a preservative blend containing phenoxyethanol and chloroxylenol, named Optiphen. When caprylyl glycol is used alone at 1% in products that are protected from contamination by fingers (i.e. bottles, jars with dispensers, pumps), the brand can make a “preservative free” claim on the product.
Due to its multi-functioning nature (antimicrobial and moisturizer), caprylyl glycol is used in a variety of personal care products, including sunscreens, anti-aging treatments, cleansers, facial moisturizers, lip gloss, mascara, and foundation.
How caprylyl glycol benefits the skin
As mentioned above, caprylyl glycol is a humectant moisturizer. Humectants are substances that absorb water from the air or underlying layers of the skin and draw those molecules toward the surface of the skin. This allows the skin to retain moisture and may also help other topical skincare ingredients to perform better.
Applying humectant moisturizers, such as caprylyl glycol, will help to keep skin hydrated. This is important not only to prevent dry skin but also to delay signs of aging. As the skin loses moisture due to both internal and external factors, it begins to show signs of aging, such as lines, wrinkles, sagging, and flaking skin. Thus, using skin care products with humectant moisturizers will help to attract moisture to the skin, resulting in smoother, softer skin with decreased wrinkles and a more plump appearance.
Unfortunately, sometimes humectant moisturizers can pull too much moisture from the lower layers of skin when the air in your surrounding environment is very dry. This can be overcome, however, if the product is formulated with occlusive moisturizers as well.
If you research caprylyl glycol, or any member of the glycol family, you’ll find that many sites warn consumers to avoid them. These sources claim that the glycols are irritating and harmful to your skin. You might even learn that glycols are found in antifreeze. This is true, but the glycol that is used in antifreeze is much different than caprylyl glycol. Glycols are a broad class of chemicals and they are not created equal.
Simply put, “glycol” is a term for any of a class of organic compounds belonging to the alcohol family; in the molecule of a glycol, two hydroxyl (−OH) groups are attached to different carbon atoms. There are many different types of compounds that belong to this family, such as propylene glycol, butylene glycol, polyethylene glycol, ethylene glycol (the glycol found in antifreeze), and more.
Caprylyl glycol is just one of the numerous glycols. While some of the glycols would most definitely be undesirable in personal care products, caprylyl glycol is not. The Cosmetic Ingredient Review (CIR) Expert Panel reviewed all available data and assessed this ingredient as safe as currently used.
References: Soap the Earth, “Caprylyl Glycol”, Healthline, “Caprylic Acid: Coconut Oil’s Secret”, Puracy, “Caprylyl Glycol”, Truth In Aging, “Caprylyl Glycol”, Making Cosmetics, “Caprylyl Glycol”, Encyclopedia Britannica, “Glycol”, Int. J. Toxicol., “Safety Assessment of 1,2-Glycols as Used in Cosmetics”, 2012.