This review provides an overview of chitosan-based nanoparticles (NPs) for non-parenteral drug delivery, highlighting their applications in various therapeutic areas. Chitosan, a biodegradable and biocompatible polymer derived from chitin, is known for its mucoadhesive properties and low toxicity, making it suitable for mucosal drug delivery. The review discusses the chemical and physical modifications of chitosan to enhance its performance in drug delivery systems, including the preparation of nanoparticles through methods such as ionotropic gelation, complex coacervation, coprecipitation, microemulsion, and emulsification solvent diffusion. Chitosan NPs exhibit sustained release and mucoadhesive properties, which are crucial for effective drug delivery to the gastrointestinal tract, nasal cavity, lungs, and brain. The review also explores the pharmacokinetics of chitosan-based formulations, their toxicity, and safety, as well as clinical vaccine trials using chitosan-based adjuvants. Overall, chitosan-based NPs show promise in improving drug bioavailability and reducing side effects, with ongoing research focusing on optimizing their formulation and application.This review provides an overview of chitosan-based nanoparticles (NPs) for non-parenteral drug delivery, highlighting their applications in various therapeutic areas. Chitosan, a biodegradable and biocompatible polymer derived from chitin, is known for its mucoadhesive properties and low toxicity, making it suitable for mucosal drug delivery. The review discusses the chemical and physical modifications of chitosan to enhance its performance in drug delivery systems, including the preparation of nanoparticles through methods such as ionotropic gelation, complex coacervation, coprecipitation, microemulsion, and emulsification solvent diffusion. Chitosan NPs exhibit sustained release and mucoadhesive properties, which are crucial for effective drug delivery to the gastrointestinal tract, nasal cavity, lungs, and brain. The review also explores the pharmacokinetics of chitosan-based formulations, their toxicity, and safety, as well as clinical vaccine trials using chitosan-based adjuvants. Overall, chitosan-based NPs show promise in improving drug bioavailability and reducing side effects, with ongoing research focusing on optimizing their formulation and application.