The present invention relates to non-thermal plasma for use in the treatment of an infected nail or infected skin, wherein the plasma is used in a method comprising: (a) applying the plasma to the infected nail or skin (b) rehydrating the infected nail or skin (c) applying the plasma to the infected nail or skin: and (d) optionally rehydrating the infected nail or skin. wherein the plasma is applied to a portion of the nail or skin in each of steps (a) and (c) until a hydration level of the plasma-treated portion drops by at most 30wt% based on the initial moisture content of the plasma-treated portion, preferably by at most 20wt%. The method may also be used to whiten, lighten or brighten a healthy nail.
