Glycerin, sometimes labeled glycerol or glycerine, is a humectant, meaning it draws water in and helps skin hold onto it. It occurs naturally in every fat molecule, whether the fat comes from a plant or an animal, and can be produced by breaking fats down or fermenting sugar. Most skincare brands, however, rely on a synthetically made version, since that process yields a purer ingredient.
What makes glycerin notable is that it's already a substance your skin produces on its own to help regulate hydration. Because of that, it's classified as a replenishing ingredient rather than an outside addition, and it plays a central role in defending skin against dryness and keeping moisture levels balanced. On its own, glycerin is an excellent hydrator, but it works even better paired with emollients and other moisture replenishing ingredients that soften and smooth skin.
Journal of Pharmaceutical Investigation, March 2021, pages 223-231 | International Journal of Toxicology, November/December 2019, Volume 38, Supplement 3, pages 6S-22S | International Journal of Cosmetic Science, August 2016, ePublication | British Journal of Dermatology, July 2008, pages 23-34 | Journal of Cosmetic Dermatology, June 2007, pages 75-82 | Proceedings of the National Academy of Sciences, June 2003, pages 7,360-7,365
Our team reviews ingredient research and uses up-to-date evidence to rate ingredients based on the categories below.
Best
Ingredients with the most rigorous and convincing evidence. These are the standouts backed by consistent findings across independent, peer reviewed clinical research.. When we call an ingredient Best, it has earned that distinction through genuine, reproducible proof that it improves skin.
Good
Reliable, well tolerated ingredients that do their job without complaint. They may not carry the headline benefits of a Best rated active, but they hydrate, stabilize a formula, or support the ingredients around them in ways that make a real difference in how a product performs and feels.
Average
Ingredients that are perfectly safe and serve a clear function, typically as an emollient, thickener, or filler, but do not offer any meaningful skin benefit beyond that basic job. Not a red flag, just not a reason to choose one product over another.
Bad/Worst
Ingredients with documented potential to irritate skin, disrupt the barrier, or trigger sensitization in some users, often synthetic fragrance, drying forms of alcohol, or certain essential oils. Not automatically a dealbreaker for every skin type, but worth knowing about before you commit to a product.
