Carboxyalkyl chitosan-based nail formulations for use in the treatment of nail inflammatory diseases like psoriasis, atopic dermatitis and lichen planus. 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 carboxyalkyl chitosan, or a salt thereof from 0.1 to 25 wt.% with respect to the total weight of the formulation.