New photodynamic, topically-applicable medicaments and certain medical uses of such photodynamic medicaments for treatment of human or animal tissue are described, wherein a primary active component of such medicaments is a halogenated xanthene. The halogenated xanthenes constitute a family of potent photosensitizers that become photoactivated upon illumination of the treatment site with visible wavelengths of light. In preferred embodiments, such medicaments are used for treatment of a variety of conditions affecting the skin and related organs； the mouth and digestive tract and related organs； the urinary and reproductive tracts and related organs； the respiratory tract and related organs； various other internal or external tissue surfaces, such as tissue surfaces exposed during surgery； and for treatment of a variety of conditions related to microbial or parasitic infection. In another preferred embodiment, such medicaments are produced in various formulations including liquid, semisolid or aerosol delivery vehicles.
