From the Research
Glycerin is an effective moisturizer typically used at concentrations between 5-10% in over-the-counter products, though it can be found in concentrations up to 20% in some formulations. For optimal moisturizing effects, look for products where glycerin appears in the first five ingredients on the label, indicating a higher concentration. Glycerin works as a humectant, drawing water from the deeper skin layers and the environment into the outer skin layer. This helps maintain skin hydration by creating a protective barrier that prevents moisture loss. According to a study published in the International Journal of Toxicology 1, glycerin is safe as a cosmetic ingredient in the practices of use and concentration described in this safety assessment.
Key Points to Consider
- Glycerin is generally well-tolerated by most skin types, including sensitive skin, making it a versatile moisturizing ingredient suitable for daily use.
- People with very dry skin may benefit from higher concentrations (10-20%), while those with normal to oily skin might prefer lighter formulations (5-10%).
- Pure glycerin should be diluted before application as it can actually draw moisture away from the skin if used at full strength.
- A study published in the Clinical, Cosmetic and Investigational Dermatology journal found that a single application of a moisturizing fluid containing 5% glycerin significantly improves skin hydration for up to 24 hours and improves skin barrier function 2.
- Another study published in the British Journal of Dermatology found that glycerol plays a role in skin hydration, cutaneous elasticity, and epidermal barrier repair, and has multiple effects on the skin, including improvement of stratum corneum hydration and skin mechanical properties 3.
Application and Concentration
For best results, apply glycerin-containing moisturizers to slightly damp skin after bathing to trap moisture. It is essential to choose a product with an appropriate concentration of glycerin based on individual skin type and needs. As noted in a study published in the European Journal of Pharmaceutical Sciences, glycerol can be used to increase skin permeability in reduced hydration conditions 4. However, the most recent and highest quality study on this topic is 2, which provides the most relevant guidance on the use of glycerin as a moisturizer.