Sunscreen and UV filters: a comprehensive review of formulation, safety, and efficacy

Photoprotection remains a critical global public health need, yet the current generation of sunscreens faces challenges related to toxicological safety, efficacy, and environmental impact. This review provides an analysis of the development of ultraviolet (UV) filters, integrating photochemistry, new formulation strategies, toxicological risks, and the regulatory landscape. The mechanisms of action of organic and inorganic filters were detailed. Inorganic filters (TiO₂ e ZnO) are effective agents, but their use can be limited by the risk of generating reactive oxygen species (ROS) and the unresolved impact of ecotoxicity, despite the potential to develop a residual white effect on the skin surface. On the other hand, several organic filters demonstrate photoinstability and raise concerns regarding systemic absorption, a critical factor emphasized by global regulatory agencies such as the Food and Drug Administration (FDA). To overcome these limitations, the review highlights strategies in nanotechnology and materials science focused on increasing filter stability and minimizing cutaneous penetration. Innovations included the nanoencapsulation of unstable UV filters and the surface functionalization of nanoparticles. Alternatives focusing on multifunctional materials such as magnesium oxide (MgO) synthesized by sustainable means were explored. MgO is presented as an alternative option due to its UV dispersion capabilities, antioxidant properties, and anti-inflammatory potential. This review synthesizes scientific data, establishing a link among filter chemistry, formulation engineering, and regulatory approval. The findings are essential to empower formulation in the development of multifunctional, safer, and eco-efficient dermocosmetic systems that promote superior consumer adherence and are aligned with global sustainability goals.