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. 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. 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. “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.
