Ironically, dry skin does not seem to be about a lack of moisture. The studies that have compared the water content of dry skin to normal or oily skin don’t seem to find a statistically significant difference in moisture content between them (Source:
Journal of Cosmetic Chemistry, September/October 1993, page 249). As mentioned in the earlier discussion of moisturizers, too much water can be a problem because it can disrupt the skin’s intercellular matrix, where the substances that keep skin cells bonded to each other are, ensuring that the outer layer of skin is intact and smooth.
What is thought to be taking place in dry skin is that the intercellular matrix has somehow become impaired or damaged, and that creates water loss. It’s not that the skin doesn’t have enough water, but rather it doesn’t have the ability to prevent water loss, or to keep the right amount of water in the skin cell.
When the intercellular matrix is disrupted, it impairs the integrity or health of the skin and the skin inevitably becomes dry, literally torn and ruptured. There are some genetic factors that create this weakened or ineffective outer layer of skin, but some of the things we do to our skin cause dryness as well.
Perhaps the biggest offense is the use of drying skin-care products such as soaps, harsh cleansers, or products with drying or irritating ingredients. All of these disrupt the outer layer of the skin, destroying the intercellular matrix and causing dry skin.
In skin-care products, the ingredients that are the worst culprits are alcohol, witch hazel, fragrance, camphor, menthol, citrus, and peppermint. Weather and the way we heat and cool our homes, cars, and workplaces are also problematic for creating or worsening dry skin.