The invention relates to a composition for topical application, comprising at least one physiologically acceptable acid capable of reducing the pH of the skin of a treated person to the range of 1.5-4.5, and a physiologically acceptable carrier. The invention further relates to various uses for the treatment of skin and nail conditions, including and especially focussing on microbiological infections of the nail (onychomycosis). The invention further relates to an applicator device and kit of parts comprising such a composition.