Our lips, with their delicate skin, are particularly vulnerable to dryness and discomfort. The superficial layers of skin are five times thinner than on the rest of the face.1 This fragile area does not produce sebum and therefore is not protected by a hydrolipidic film.2 What's more, our lips are constantly exposed to environmental stressors like the cold and wind, as well as humidity.3 Plus, we frequently moisten our lips throughout the day., and contrary to popular belief, saliva dries out the skin even more.
1 S. Kokil, M. Kadu, D. Vishwasrao, and D. Singh, “Review on Natural Lip Balm,” International Journal of Research in Cosmetic Science, vol. 5, p. 1, Aug. 2014.
2 J. Kim, H. Yeo, T. Kim, E. Jeong, J. Lim, and S. Park, “Relationship between lip skin biophysical and biochemical characteristics with corneocyte unevenness ratio as a new parameter to assess the severity of lip scaling,” International Journal of Cosmetic Science, vol. 43, Feb. 2021, doi: 10.1111/ics.12692.
3 M. Rinnerthaler et al., “Age‐related changes in the composition of the cornified envelope in human skin,” Experimental Dermatology, vol. 22, no. 5, pp. 329–335, May 2013, doi: 10.1111/exd.12135.