Dry Skin

Dry skin, medically xerosis, is not simply skin that lacks water — it is skin whose permeability barrier has failed. The stratum corneum works as a brick-and-mortar structure: corneocytes are the bricks, and the mortar is a lamellar matrix of ceramides, cholesterol and free fatty acids in roughly equal proportion. When that lipid mortar is depleted, transepidermal water loss rises, the corneocytes shrink and crack, and you get the rough, flaky, tight feeling that defines the condition. This matters practically because it explains why drinking more water rarely fixes dry skin while restoring lipids usually does. It also explains why hot showers, harsh surfactants, low humidity and over-exfoliation are the most common causes: each strips or disrupts the lipid matrix directly. Age is the other dominant factor. Sebum production and ceramide content both fall progressively from the forties onwards, which is why xerosis is near-universal in older adults. When dryness is severe, sudden or unresponsive to good topical care, it is worth screening for hypothyroidism, iron deficiency, diabetes, chronic kidney disease, and deficiencies of essential fatty acids, vitamin A or zinc — all of which present with dry skin before more obvious signs.

• •Rough, flaky or scaly texture
• •Feeling of tightness, especially after washing
• •Itching, sometimes worse at night
• •Fine cracks or fissures, often on hands, heels and shins
• •Ashy or greyish appearance on deeper skin tones
• •Redness and irritation in affected areas
• •Skin that stings when moisturiser or products are applied

• •Age-related decline in ceramide and sebum production
• •Hot showers and harsh surfactant-based cleansers
• •Low ambient humidity and indoor heating
• •Over-exfoliation or overuse of retinoids and acids
• •Hypothyroidism
• •Iron deficiency
• •Essential fatty acid deficiency from very low fat intake
• •Vitamin A or zinc deficiency
• •Diabetes and chronic kidney disease
• •Diuretics, statins, retinoids and other medications

{"Depletion of the stratum corneum lipid matrix — ceramides, cholesterol and free fatty acids","Elevated transepidermal water loss from barrier breakdown","Reduced natural moisturising factor within corneocytes","Disrupted filaggrin processing, which underlies both eczema and constitutional dryness","Systemic drivers such as thyroid dysfunction reducing sebum and sweat output"}