Collagen (CLG) belongs to the family of fibrillar proteins and is composed of left-handed α polypeptide chains, which, twisting around themselves and their axis, form a right-handed superhelix. In the chemical structure, it contains mainly proline, hydroxyproline, glycine, and hydroxylysine. It occurs naturally in the dermis in the form of fibers that provide the skin with proper density and elasticity. The review aimed to present the types of collagen protein, factors affecting its structure and its unusual role in the functioning of the human body. Also, an overview of cosmetic products containing collagen or its derivatives, the characteristics of the formulas of these products, and the effects of their use were presented. Throughout the market, there are many cosmetic and cosmeceutical products containing CLG. They are in the form of fillers administered as injections, belonging to the group of the oldest tissue fillers; products administered orally and for topical use, such as creams, gels, serums, or cosmetic masks. Analyzed studies have shown that the use of products with collagen or its peptides improves the general condition of the skin and delays the aging process by reducing the depth of wrinkles, improving hydration (in the case of oral preparations), reducing transepithelial water loss (TEWL), as well as improving skin density and elasticity. In addition, oral application of bioactive CLG peptides has shown a positive effect on the nails, reducing the frequency of their breakage.

Nanosomes—lipid vesicles at the nanoscale—enable the encapsulation of both hydrophilic and lipophilic actives and are increasingly used as skin delivery systems in cosmetic products. Alongside nanoemulsions, polymer nanocapsules, and inorganic nanoparticles (e.g., TiO₂, ZnO, Ag), they can enhance solubility, stability, residence time, and local bioavailability while enabling controlled release. This review summarizes nanocarrier structures, preparation concepts, and skin penetration pathways (transepidermal intercellular/transcellular and transappendageal), and discusses formulation factors that modulate delivery. We highlight applications in UV protection, anti-aging, and fragrance retention, focusing on lipid-based systems (liposomes/nanosomes, ethosomes, niosomes). Safety considerations are critically appraised with reference to EU and FDA frameworks, including physicochemical characterization, dermal penetration, irritation/sensitization, and genotoxicity testing. While most data indicate limited penetration through intact skin for particles ≥20 nm, enhanced uptake may occur under specific conditions (very small size, barrier impairment, mechanical stress), warranting careful risk assessment. We conclude with regulatory and sustainability perspectives and outline research priorities for long-term toxicology, in-use exposure, and standardization of methods.