Abstract: The invention relates to the field of therapeutic chemistry and concerns novel antiviral pharmaceutical compositions for the local prevention of diseases of the genital and rectal mucus membranes. The compositions are characterized in that that the active ingredient used is riboflavin or one of the mineral or organic acid or FAD addition salts thereof. The active ingredient further comprises niacin or NAD or NADP. Vitamin factors can also be added such as carotene, flavonoids, acetyloenzyme A and vitamins A, E, C, B6, B8 or F. Fillers such as insoluble barium salts, titanium derivatives, alkaline-earth silicates, aluminium silicates, mineral or organic bismuth salts, insoluble zinc salts, rare earth derivatives, zirconium derivatives, can be added to said compositions to reinforce the mucus adhesiveness of said preparations. Vegetable extracts containing flavonoids or anthocyanosides can be further incorporated into the pharmaceutical compositions of the invention.