Abstract: The present invention relates to a method for counteracting infections caused by bacteria, fungi or virus such as Herpes Simplex Virus in skin or mucosal membranes, in particular genital membranes, of a mammal. The method comprises topically administering to the skin or mucosal membrane an effective amount of a formulation comprising a) at least one microbicidal lipid, b) at least one solubilizing agent which keeps the lipid dissolved in the formulation, and optionally 3) a gel-forming agent. The formulation used in the method may suitable be in the form of a hydrogel. The microbicidal lipid is preferably a C6-18 fatty acid, such as, e.g., lauric acid, or a derivative thereof, e.g., a monoglyceride such as capric acid 1-monoglyceride. The solubilizing agent may suitably be a glycofurol such as the commercially-available glycofurol 75. The invention also relates to novel pharmaceutical formulations for use in the method.