Glycerin

Glycerin stands out as one of skincare's most beneficial and well-researched ingredients, particularly for those with dry or sensitive skin types. This naturally occurring molecule acts as a powerful humectant, drawing water into the skin and helping to maintain optimal hydration levels [1]. Research demonstrates that glycerin not only improves skin hydration but also strengthens the skin barrier, reduces inflammation, and helps prevent moisture loss [2].

For those with dry sensitive skin (Type 1) or dry skin (Type 2), glycerin is particularly valuable as it reduces what scientists call "drying stresses" - the mechanical forces that can lead to skin irritation and damage [3]. Studies show that glycerin helps maintain skin lipids in a healthy state, even in low humidity conditions, which is especially beneficial for these skin types [4]. Those with balanced (Type 3) or oily skin types (Types 4 and 5) can also benefit from glycerin's ability to provide hydration without adding excess oil or causing congestion, as it's been proven to be non-comedogenic [5].

The optimal concentration of glycerin in skincare products ranges from 5-20%, with research showing significant improvements in skin hydration and barrier function within this range [6]. Most effectively, glycerin works in formulations that combine it with other moisturizing ingredients, creating a synergistic effect that benefits all skin types [8].

Scientific studies have consistently demonstrated glycerin's exceptional safety profile, with extremely low rates of irritation or sensitization across all skin types [9]. This makes it particularly suitable for those with sensitive skin conditions, including rosacea and eczema. Its ability to enhance the skin's barrier function can help protect against environmental damage while supporting the skin's natural repair processes [10].

References:

[1] Lodén M, Wessman C. 'The influence of a cream containing 20% glycerin and its vehicle on skin barrier properties.' International Journal of Cosmetic Science. 2001;23(2):115-119. DOI: 10.1046/j.1467-2494.2001.00060.x

[2] Becker L, et al. 'Safety Assessment of Glycerin as Used in Cosmetics.' International Journal of Toxicology. 2019;38(3):6S-22S. DOI: 10.1177/1091581819883820

[3] Levi K, et al. 'Effect of glycerin on drying stresses in human stratum corneum.' Journal of Dermatological Science. 2011;61(2):129-150.

[4] Chen HJ, et al. 'Moisture retention of glycerin solutions with various concentrations: a comparative study.' Scientific Reports. 2022;12:10232. DOI: 10.1038/s41598-022-13452-2

[5] Formula Botanica. 'Glycerin Documentation.' 2022.

[6] Fluhr JW, et al. 'Glycerol accelerates recovery of barrier function in vivo.' Acta Dermato-Venereologica. 1999;79:418-421.

[7] Batt MD, Fairhurst E. 'Hydration of the stratum corneum.' International Journal of Cosmetic Science. 1986;8:253-264.

[8] Rawlings AV, et al. 'The effect of glycerol and humidity on desmosome degradation in stratum corneum.' Archives of Dermatological Research. 1995;287:457-464.

[9] Hannuksela M, Förström L. 'Contact hypersensitivity to glycerol.' International Journal of Dermatology. 1979;1(5):257-263.

[10] Froebe CL, et al. 'Prevention of stratum corneum lipid phase transitions in vitro by glycerol - An alternative mechanism for skin moisturization.' Journal of the Society of Cosmetic Chemists. 1990;41:51-65.