Synopsis

Source of validity: Scientific
Rating (out of 5): 2

Keratin is a fibrous structural protein naturally found in the skin, hair, and nails. In cosmetic and skin care products, hydrolyzed keratin is sometimes included with the aim of improving skin barrier function and moisture retention. Scientifically, keratin is known for its structural role in the stratum corneum, the outermost layer of the skin, where it helps provide protection and resilience. Some laboratory and animal studies suggest that hydrolyzed keratin may help improve skin hydration and repair the barrier function by forming a protective film on the skin surface.

However, evidence supporting topical keratin’s effectiveness in general skin care is limited. Most studies focus on its use in hair care, with few clinical trials evaluating direct benefits for human skin. The large molecular size of intact keratin limits its ability to penetrate the skin, so most products use hydrolyzed forms. Even so, clinical data demonstrating significant or lasting improvements in skin health, beyond basic moisturization, are sparse.

Therefore, while keratin’s inclusion in skin care is based on its known biological role and some laboratory studies, robust scientific validation in human skin care applications is lacking. The current evidence supports at best a modest benefit, mainly related to barrier support and hydration when hydrolyzed keratin is used, justifying a low-to-moderate evidence rating.

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