keratolytic

Keratolytic refers to agents that promote shedding of the stratum corneum, the outermost layer of the skin, by weakening keratin bonds or dissolving the intercellular cement that holds corneocytes together. These agents are used to treat thickened, rough, or scaling skin and to improve the penetration of other topical therapies.

The mechanism of action typically involves loosening or breaking down the connections between skin cells, increasing desquamation and turnover. Some keratolytics, such as salicylic acid, work by reducing intercellular cohesion and altering the skin’s pH, while alpha-hydroxy acids (glycolic and lactic acids) promote exfoliation by increasing cell turnover. Urea has a humectant effect at low concentrations and keratolytic action at higher concentrations, softening the horny layer. Retinoids (tretinoin, adapalene, tazarotene) promote abnormal keratinocyte differentiation and turnover, contributing to keratolysis in acne and hyperkeratotic conditions. Sulfur-containing preparations also have keratolytic properties and are used in some dermatologic formulations.

Common clinical uses include treatment of warts (verrucae), corns and calluses, other hyperkeratotic scales, acne, and rough or photo-damaged skin. They may also aid in the removal of plaque in certain hyperkeratotic disorders and enhance the effectiveness of other topical medications by improving penetration.

Safety and practical considerations include potential skin irritation, redness, burning, or dryness, especially with higher concentrations or prolonged use. Some keratolytics increase photosensitivity and require sun protection. Use should be guided by indications, skin type, and concurrent therapies, with attention to contraindications in pregnancy for specific agents and in cases of damaged or broken skin.

See also keratolysis and keratinization.