Nasal or sinus sites are treated with a ready-to-use paste having a high concentration of a water-soluble chitosan and an osmolality reducing agent dissolved in a phosphate- containing solution. The ingredients provide a paste at room temperature and have a pH of at least 4. The osmolality reducing agent does not crosslink with the water-soluble chitosan. The paste provides stenting, adheres to the nasal or sinus site and has a residence time of at least 1 day.
