What is Glycerin?
Glycerin, also called glycerol, is one of the most widely used and longest-studied moisturizing ingredients in skincare. It occurs naturally in skin as part of the skin's own natural moisturizing factor, and is also found in plant oils and produced synthetically for cosmetic use. Because of its long track record and strong safety and efficacy data, glycerin is considered something of a gold standard among humectants, the category of ingredients that help skin attract and hold onto water.
Source
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Found in |
Naturally present in skin, as well as in plant and animal fats |
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Origin |
Naturally derived from plant oils, or produced synthetically for cosmetic use |
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Also known as |
Glycerol |
Top features and benefits
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Helps skin attract and hold onto moisture |
Supports faster skin barrier repair after damage |
Helps stabilize the structure of the skin's outer lipid layer |
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One of the most extensively clinically studied humectants |
Generally well tolerated, including on sensitive skin |
Works well in combination with other humectants like hyaluronic acid |
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Suitable for most skin types |
Naturally occurring in skin already |
How Does It Work?
Glycerin enters skin partly through a specific water-and-glycerol transport channel called aquaporin-3, and it is also naturally present on the skin's surface from the breakdown of oils produced by sebaceous glands. Once there, its most well-known role is as a humectant, drawing water in and helping skin hold onto it, which is why glycerin-containing products so reliably improve measured skin hydration in clinical studies.
Beyond simply attracting water, research suggests glycerin has a second, less commonly discussed role: helping stabilize the structure of the lipids in the outer layer of skin, keeping that protective layer more flexible and intact, particularly in low-humidity conditions where lipids might otherwise become more rigid. Studies in mice lacking the aquaporin-3 channel found that their impaired skin barrier could be corrected by applying glycerin directly, but not by simply hydrating the skin with water alone, suggesting glycerin plays a distinct, structural role beyond basic moisture attraction.
In a controlled clinical study, a cream containing 20 percent glycerin significantly increased skin hydration, measured with a corneometer, after 10 days of use, and supported healthier skin barrier function under stress testing compared to a glycerin-free version of the same cream.