This essential protein is a vital building block of the skin’s outer layer. It gives strength, resilience, and protection. While not usually applied topically in facial skincare, understanding its role helps explain how skin maintains its barrier and how certain conditions arise when keratin production goes off balance.
What is it?
Keratin is a tough, fibrous protein that plays a central role in the structure of skin, hair, and nails. In the skin, keratin helps form the outermost layer of the epidermis, creating a barrier that protects against environmental damage, prevents water loss, and keeps out bacteria and irritants.
Produced by specialised cells called keratinocytes, keratin builds up as these cells move upward through the layers of the epidermis. By the time they reach the skin’s surface, the keratinocytes have died and hardened, forming the stratum corneum. This layer is made almost entirely of flattened, keratin-rich cells embedded in a lipid matrix. Together, they form the skin’s natural barrier.
Where is it used?
The protein itself is not usually added as a skincare ingredient in facial products, as it is a large molecule that cannot easily penetrate the skin. However, in hydrolysed form, which is broken down into smaller fragments, it is sometimes used in haircare and nail products to help strengthen and smooth damaged fibres. In these cases, it can temporarily fill in gaps in the cuticle or nail plate, giving a healthier appearance.
In skin conditions like keratosis pilaris or psoriasis, keratin production can become excessive or abnormal, leading to a build-up of rough, scaly skin. These conditions are often managed with exfoliants like AHAs, BHAs, or urea, which help loosen and remove excess keratin from the skin’s surface.
What does it do?
It also plays a role in wound healing, forming part of the structural scaffold as the skin repairs itself. In healthy skin, the production and shedding of keratin is a continuous process, renewing the epidermis roughly every four weeks.
Maintaining the skin’s natural keratin structure involves keeping the barrier intact. This means avoiding over-exfoliation, using moisturisers to replenish lipids, and protecting against UV damage. While keratin helps toughen and shield the skin, it works best as part of a balanced, functioning barrier.
