Barrier Function
Definition
The skin's barrier function refers to the protective role of the outermost layer of the epidermis, the stratum corneum. Often described using the 'bricks and mortar' analogy, the barrier consists of dead skin cells (corneocytes, the bricks) held together by a lipid matrix of ceramides, cholesterol, and fatty acids (the mortar). A healthy barrier prevents excessive water loss from the body (transepidermal water loss) and keeps out irritants, allergens, and pathogens. When the barrier is compromised — through over-exfoliation, harsh cleansers, environmental damage, or conditions like eczema — the skin becomes dry, sensitive, red, and reactive. Restoring barrier function involves using gentle cleansers, ceramide-rich moisturizers, and avoiding known irritants while the skin heals.
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