Abstract: The present invention affords means for decontaminating biological fluids such as blood and blood components. The method involves contacting a biological fluid with a diphenylpyrilium compound, and irradiating the mixture with red light. The method is a potent and effective means for eliminating or diminishing active pathogens such as viruses, bacteria, and parasites, without causing substantial hemolysis or otherwise degrading the storage stability of the decontaminated biological fluid.

Abstract: The invention provides a method for reducing the level of active pathogenic contaminants, such as viruses, bacteria and parasites, found in whole blood and blood components. The method comprises adding to a red blood cell-containing composition at least one phenothiazin-5-ium dye in an amount effective to reduce the level of active pathogenic contaminants and at least one blocking compound in an amount effective to enhance pathogen inactivation and protect red blood cells from hemolysis, and irradiating the red blood cell-containing composition with light of an appropriate intensity and wavelength for a time sufficient to reduce the level of active pathogenic contaminants in the red blood cell-containing composition. An irradiated red blood cell-containing composition comprising red blood cells, a phenothiazin-5-ium dye and a blocking compound is also provided.