A method applying a composition to a human or non-human individual or to an object or a surface area and a pharmaceutical composition with a regimen of administering it to a human or non-human individual is provided. The composition includes an active chemical component for killing of or retarding proliferation of target cells including pathogens, infected cells and cancer cells. The application of the composition and the regimen of administration of the composition are accompanied by at least one exposure to electromagnetic radiation in a range of wavelengths in which the active chemical component absorbs and which has a lower limit of 190 nm, thereby photo-activating the active component.
