Poor cleansing: Any cleanser leaving the skin squeaky clean or even taut is dehydrating. Soap is harsh because it is alkaline, stripping the hydrolipidic film and leaving the horny layer exposed, unprotected and subject to moisture loss. Other alkaline washes, such as densely foaming soaps or alcohol solutions used for oily and problem skin, are even worse since they produce closed comedones, which become blackheads and possible pustules. Harsh scrubs can break down cell cohesion in certain skin types and place capillaries at risk.
Skin damage: Harsh acne treatments, such as hydrogen peroxide, retinoic acid and benzoyl peroxide, alter the keratinization process and weaken the ability of the cells in the horny skin to bond together.
Lifestyle/neglect: Some examples include the failure to drink a sufficient amount of fluid and to apply moisturizers daily. Cigarette smoking reduces the flow of moisture and nutrition to the cells (vasoconstriction), and high consumption of alcohol is excessively dehydrating.
Medications: Some dehydrating medications include diuretics for hypertension (high blood pressure) or heart failure. Isotretinoin shuts down the sebaceous glands, which lead to dehydration. Other dehydrating meds include cold and flu remedies, and cortisone
Astringents: Alcohol-based tonics wiped on skin remove sebum and strip skin like a strong cleanser.
Central heat/air: Water loss from the skin is increased by dry winter air, either outside on cold, frosty mornings or inside centrally heated homes or offices. Wind increases evaporation of the skin.
Hot showers: The friction and heat of hot water remove sebum from the skin’s surface, inviting capillary damage and dehydration. Always wash your face separately using lukewarm water only.
Diet: An excessive intake of table salt (sodium chloride) can have a dehydrating effect. Coffee/alcohol can also contribute dehydration.