The present invention provides a method of treating and preventing the common cold and associated secondary illnesses in a human subject, when the common cold is caused by viruses. The method comprises applying to the nasal passages of the human subject at ambient temperature, an effective amount of a pharmaceutical preparation comprising povidone-iodine (PVP-I) at a concentration of greater than 0.10% w/v and less than 2.5% in which at least 50% of the PVP-I is not associated with liposomes or other particulate carriers.
