What Is Caprylyl Glycol? We Explain This Common Skin Care Preservative
Caprylyl glycol is an ingredient that's frequently found in personal care products. But thanks to its nearly unpronounceable name, you might instinctively raise a brow when you find it on ingredient decks. Don't worry, though—this tongue twister of a compound is on your side. Here, we explain what it is and why it's used in so many formulas.
What is caprylyl glycol?
Caprylyl glycol is an alcohol that comes from a caprylic acid, a type of fatty acid. (Caprylic acid is a natural component of coconut oil, palm kernel oil, and the milk of some mammals.) But don't let the "alcohol" part scare you. Since it comes from a fatty acid, caprylyl glycol is the kind of alcohol that isn't sensitizing or drying.
Structurally, caprylyl glycol is a long chain of eight carbons. It's a diol (or glycol), which means it has two hydroxyl groups. (A hydroxyl group is simply an oxygen bonded with a hydrogen; it's what makes this compound an alcohol.) One is located on the first carbon, and another is on the second. Thus, it's also called 1,2-octanediol. The 1,2- indicates the positions of the hydroxyl groups, while the octo- prefix refers to the number of carbons.
Caprylyl glycol takes the form of a liquid. According to board-certified dermatologist Loretta Ciraldo, M.D., FAAD, it has a slightly sweet scent and neutral color. On ingredient decks, it's also listed as capryl glycol, 1,2-octanediol, 1,2-dihydroxyoctane, 1,2-octylene glycol, or octane-1,2-diol.
What is caprylyl glycol used for in skin care?
In skin care, "this ingredient is a true multitasker," says Ciraldo. It's mainly used to improve the composition and shelf life of nontoxic formulas, but it has some benefits for the skin too. Here's a look at its many talents:
1. It fights bacteria.
Due to their water content, skin care products are the perfect breeding ground for bacteria. But when ingredients like caprylyl glycol are added to the mix, you can rest easy knowing that your formulas are safe. The compound exhibits moderate antibacterial activity, which reduces your risk of developing a skin infection. Phew.
2. It acts as a preservative.
The antibacterial effects of caprylyl glycol also delay the risk for spoilage. This extends a product's shelf-life, says Ciraldo, allowing you to get the most out of it. In fact, caprylyl glycol is frequently used to replace conventional (and questionable) preservatives like parabens and formaldehyde releasers.
It can't work alone, though. "In skin care formulations, preservative systems should work against overgrowth of both fungus and bacteria," explains Ciraldo. "Caprylyl glycol only works to stop bacterial overgrowth," so it's typically used with other safe preservatives like phenoxyethanol, a low-risk alternative for parabens.
3. It moisturizes the skin.
Caprylyl glycol is a humectant agent, notes Ciraldo. That means it hydrates your complexion by attracting—and retaining—water. It also has conditioning properties, so it softens the skin and hair. For this reason, caprylyl glycol is commonly added to moisturizing products like hair conditioners and eye creams.
4. It improves the application of a product.
Caprylyl glycol is amphiphilic—a fancy word for a chemical with hydrophilic (water-loving) and lipophilic (fat-loving) parts. The hydrophilic portions interact with water, while the lipophilic portions interact with fat. This reduces the surface tension between water and oil, making it ideal for emulsifying formulas with both ingredients. The result? A product that spreads like a dream.
Bonus: With its neutral scent and color, caprylyl glycol won't mess with the original formula. It's also very stable when added to products, says Ciraldo.
Are there side effects?
Caprylyl glycol is rarely associated with side effects, notes Ciraldo. Plus, according to the Cosmetic Ingredient Review (CIR) Expert Panel, caprylyl glycol is considered safe. One study also found that a gel with capyryl glycol and 1,2-hexanediol (a similar preservative) doesn't cause skin sensitivity.
"Another glycol, [called] propylene glycol, is a common sensitizer," Ciraldo adds. "Sometimes consumers mistakenly believe that all glycols are the same—but this is not the case."
However, even alternative preservatives like caprylyl glycol aren't 100% risk-free. Some people may still develop adverse side effects like irritation or sensitivity after using it. These instances are uncommon, though, and typically happen after applying the ingredient at unusually high concentrations. Luckily, caprylyl glycol is diluted when added to skin care products, so the amount present is low. This reduced concentration—along with correct application according to a product's directions—should keep unpleasant side effects at bay.
Caprylyl glycol is one of those ingredients that works behind the scenes. Instead of fueling the main intent of a product, it works by extending shelf life and enhancing application. You can find it in a variety of formulas, including sunscreens, shampoos, lipsticks, and bronzers.
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