Barrier impairment

Barrier impairment describes a state in which the skin's outermost layer is no longer holding water in and keeping irritants out as effectively as it should. The stratum corneum works a little like brickwork: flattened cells set in a mortar of ceramides, cholesterol and fatty acids. When that lipid mortar is depleted or disorganised, transepidermal water loss rises and substances that would normally stay on the surface penetrate more easily.

Everyday causes include over-exfoliation, too many actives at once, harsh or strongly alkaline cleansers, hot water, low humidity, wind and friction. Impairment also accompanies conditions such as eczema, and susceptibility varies with age, genetics and climate.

Commonly reported signs are tightness, stinging from products that used to feel comfortable, flaking, dullness and easily triggered redness. These are descriptive, not diagnostic. Pausing actives and returning to a simple, gentle routine is the usual first response; persistent, painful, cracked or spreading symptoms should be assessed by a dermatologist rather than self-managed.