Incorporating deep eutectic solvents into polymer-based drug delivery systems (DDS) offers a sustainable route to enhance solubility, modify drug release, and create dual-function carriers. This review explores how DES influence polymer structures and DDS performance, highlighting future prospects in personalized, responsive pharmaceutical technologies. Created in BioRender. Nining, N. (2025) https://BioRender.com/kc12by9.

Incorporating deep eutectic solvents (DES) into polymer-based drug delivery systems (DDS) presents a novel approach to addressing persistent pharmaceutical issues, including low solubility, restricted bioavailability, and unregulated drug release. As environmentally friendly, adjustable, and biocompatible alternatives to traditional organic solvents and ionic liquids, DES possess distinctive physicochemical characteristics—such as strong hydrogen-bonding ability, low volatility, and structural flexibility—that make them effective as functional excipients. This review consolidates a contemporary understanding of the formulation and performance of polymeric matrices containing DES, highlighting their capacity to alter drug release kinetics, improve solubility, and facilitate dual-function systems like therapeutic DES (THEDES). A comprehensive overview of the various types of DES and polymeric carriers, their methods of integration, associated physicochemical effects, and drug release mechanisms is provided. Furthermore, the outline problems associated with stability, sterilization, and regulatory considerations. In addition, the most prospective future uses of DES–polymer systems is examined in stimuli-responsive systems, 3D-printed scaffolds, and advanced tailored medicine. This article supports the broader polite investigation of polymers and DES in polymeric systems in DDS as a significant step toward safer, more environmentally friendly, high-efficiency pharmaceutical technologies.