The invention relates to a dermatological treatment device suitable primarily for treating nail fungus, in particular toenail fungus. The use of a photochemically active substance allows effective control of the fungus by irradiating with light at a wavelength that is relatively harmless to health. Potential technical implementations are possible for setting up the irradiation device, utilizing either a gas discharge lamp or LEDs as the light source. A shoe-shaped optical shielding housing is preferably used, being transparent in the long-wavelength portion of the visible spectrum, and absorptive in the short-wavelength, therapeutic range of the spectrum.
