Hydroxyproline is a non-proteinogenic amino acid predominantly found as a structural component of collagen — the most abundant protein in human connective tissues. In the context of skincare formulations, hydroxyproline and its derivatives (such as dipalmitoyl hydroxyproline) are valued for their role in collagen stabilization, fibroblast stimulation, and anti-aging support. Topical applications aim to enhance skin firmness, elasticity, and hydration by promoting collagen synthesis and counteracting the natural degradation processes that occur with chronological and photo-aging. The molecular structure of hydroxyproline allows it to participate in hydrogen bonding with water molecules, contributing to increased moisture retention in the stratum corneum, which improves barrier integrity and overall skin texture. Products leveraging hydroxyproline are frequently positioned in anti-aging serums, firming creams, eye treatments, and post-procedural repair systems designed to reduce fine lines and improve skin resiliency.

Although direct evidence for hydroxyproline’s efficacy in haircare is less pronounced, amino acids related to collagen metabolism have been incorporated into hair conditioners and leave-in treatments to support hair strength, conditioning, and cuticle smoothing through similar mechanisms of protein support and hydration. In this context, hydroxyproline derivatives may help maintain scalp health and improve hair manageability by reinforcing the structural environment of the hair follicle and shaft, although more targeted research is warranted to fully define these effects in haircare.