Red blotches on the skin such as those associated with environmental stresses, or red blotches associated with a skin disorder, for example those occurring during rosacea, are treated/reduced by administering to individuals afflicted therewith, thus effective amounts of at least one extract of a non-photosynthetic and non-fruiting filamentous bacterium cultured in a medium which includes at least one non-sulfurous mineral and/or thermal water, e.g., an extract derived from the bacterium Vitreoscilla filiformis, in particular the strain ATCC 15551, cultured in a medium enriched with water from La Roche Posay.