Biocompatibility, biodegradability, and low toxicity make chitosan a promising medication delivery agent. It has trouble crossing the BBB. Several methods can improve chitosan's BBB crossing. Nanoparticle formulation, surface modification, conjugation with lipid carrier systems, Focused ultrasound technique (FUS), intranasal delivery, Complexation with CPPs, and particle size and charge optimization are examples. Surface changes with targeted ligands and nanoparticles can improve BBB penetration. Through olfactory and trigeminal nerve pathways, intranasal administration bypasses the BBB.