The present invention includes the utility of anti-viral and / or antibacterial effective amounts of 6-substituted nucleoside derivatives of formula (I) (e.g. 6-iodouridine and 6-iodouridine monophosphate) in the treatment or prevention of viral infections (e.g. Flavivridae, Bunyaviridae, or Togaviridae, or viral infections of hepatitis C, hepatitis B, herpes, influenza, HIV, polio, Coxsackie A / B, rhino, small pox, Ebola, West Nile, or corona virus) and / or bacterial infections (e.g. H. pylori, S. Aureus, B. anthracis, Mycobacterial tuberculosis, M. leprae, M. avium, P. aueruginosa, Streptococcal species, and Pneumocystis carinii).