An inexpensive, easily available, and convenient method of treating or preventing a virus infection is provided. The present invention relates to a method for the treatment or prevention of virus infections using polybiguanide-based compounds administering a therapeutically effective amount of a compound or a pharmaceutically acceptable salt thereof. The invention relies on the unique biochemical reaction in which polybiguanide-based compounds interfere with the spread of virus within or between organisms. The compositions and formulations described in the present invention are effective means to reduce the infectivity of the human immunodeficiency virus type 1 (HIV-1), and human herpes simplex viruses, and also to kill the causative organisms of many other sexually transmitted diseases (STDs).