Therapeutic deep eutectic systems (THEDES) are emerging as promising alternatives to traditional solvents in pharmaceutical applications due to their unique properties such as low toxicity, high tunability, and biodegradability. These systems are formed by mixing drugs with deep eutectic solvents (DESs) in a specific molar ratio, enhancing drug solubility, permeability, and bioavailability. DESs, a new class of green solvents, are non-toxic, cheap, and easy to prepare, making them ideal for pharmaceutical use. THEDES have shown potential in various drug delivery routes, including transdermal, oral, intravenous, buccal, and vaginal delivery, improving drug stability, solubility, and controlled release. They are also effective in enhancing the solubility and permeability of poorly soluble drugs, which is crucial for drug absorption and efficacy. The application of THEDES in drug delivery systems has been explored through various fabrication techniques such as electrospinning, self-emulsification, supercritical fluid technology, nanoprecipitation, and others. These systems have been successfully used in the delivery of various drugs, including anti-tuberculosis, anticancer, and antimicrobial agents, as well as in wound healing and hepatotoxicity management. Additionally, THEDES have shown potential in stabilizing bioactive compounds, enhancing the stability of enzymes and proteins, and improving the efficacy of biopharmaceutical formulations. The use of natural deep eutectic systems (NADES) further highlights the potential of these systems in sustainable and environmentally friendly drug delivery applications. Overall, THEDES offer a promising approach for improving drug delivery and bioavailability, with significant implications for the pharmaceutical industry.Therapeutic deep eutectic systems (THEDES) are emerging as promising alternatives to traditional solvents in pharmaceutical applications due to their unique properties such as low toxicity, high tunability, and biodegradability. These systems are formed by mixing drugs with deep eutectic solvents (DESs) in a specific molar ratio, enhancing drug solubility, permeability, and bioavailability. DESs, a new class of green solvents, are non-toxic, cheap, and easy to prepare, making them ideal for pharmaceutical use. THEDES have shown potential in various drug delivery routes, including transdermal, oral, intravenous, buccal, and vaginal delivery, improving drug stability, solubility, and controlled release. They are also effective in enhancing the solubility and permeability of poorly soluble drugs, which is crucial for drug absorption and efficacy. The application of THEDES in drug delivery systems has been explored through various fabrication techniques such as electrospinning, self-emulsification, supercritical fluid technology, nanoprecipitation, and others. These systems have been successfully used in the delivery of various drugs, including anti-tuberculosis, anticancer, and antimicrobial agents, as well as in wound healing and hepatotoxicity management. Additionally, THEDES have shown potential in stabilizing bioactive compounds, enhancing the stability of enzymes and proteins, and improving the efficacy of biopharmaceutical formulations. The use of natural deep eutectic systems (NADES) further highlights the potential of these systems in sustainable and environmentally friendly drug delivery applications. Overall, THEDES offer a promising approach for improving drug delivery and bioavailability, with significant implications for the pharmaceutical industry.