Moisturization

Moisturization is the set of strategies used to maintain or restore the skin's moisture content and barrier function. In humans, the outermost layer of the skin, the stratum corneum, acts as a barrier to water loss. Moisturizers aim to increase water content or reduce water loss, thereby improving elasticity, softness, and comfort. Adequate moisturization is beneficial for dry skin, aged skin, and many dermatologic conditions.

Moisturizers work through three interrelated actions: humectants attract water from the dermis or atmosphere; occlusives form a physical barrier to water loss; and emollients fill in microcrevices between skin cells to improve smoothness. Many products combine these actions and may support the skin’s lipid barrier, including ceramides and cholesterol.

Common moisturizer forms include creams, lotions, and ointments. Ingredients often fall into three categories: humectants such as glycerin, propylene glycol, sorbitol, and hyaluronic acid; emollients such as fatty alcohols, esters, oils, squalane, and dimethicone; and occlusives such as petrolatum, mineral oil, and heavier butters. The choice depends on climate, skin type, and condition. Ointments provide strong occlusion and are best for very dry areas; creams and lotions are lighter and easier to apply.

Usage and safety: apply to slightly damp skin after bathing to trap moisture; use as part of daily care or during flares of dry skin. Patch test new products for irritation or allergy. Fragrance-free formulas may be preferable for sensitive skin. In daytime, pairing moisturizers with broad-spectrum sunscreen improves protection and skin health.