The lyophilized infusion from flowers of Verbascum thapsiforme Schrad. (FVI) showed antiviral activity in in vitro studies against Fowl plague virus, several influenza A strains, influenza B strain as well as Herpes simplex virus. Influenza viruses titer decreased by 1-3 log units, while of H. simplex virus by 2.3 log. FVI has shown virucidal activity on H. simplex virus at 300 micrograms/ml, but did not inactivate influenza viruses. Phytochemical investigations of FVI have shown the presence of flavonoids, iridoids, phenolic acids, saponins, amino acids and free sugars.