CHITOSAN-BASED NAIL FORMULATIONS ARE USEFUL TO TREAT NAIL INFLAMMATORY DISEASES LIKE PSORIASIS, ATOPIC DERMATITIS AND LICHEN PLANUS. THE CHITOSAN IS NORMALLY IN THE FORM OF AN AMINO-POLYSACCHARIDE DERIVATIVE, PREFERABLY WATER SOLUBLE, SUCH AS HYDROXYPROPYL 10 CHITOSAN. THE FORMULATION MAY BE A NAIL LACQUER, A SPRAY, A CREAM, AN OINTMENT, A GEL, A LOTION OR A FOAM AND MAY HAVE A CONTENT IN CHITOSAN, CHITOSAN DERIVATIVE OR A SALT THEREOF FROM 0.1 TO 25 WT.% WITH RESPECT TO THE TOTAL WEIGHT OF THE FORMULATION.