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 a derivative, preferably water soluble, such as hydroxypropyl 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.
