What other conditions can look like oral herpes (cold sores)? Primary herpes refers to the first episode of symptoms after infection, often presenting with painful sores on the lips, gums, and mouth. HSV-2, on the other hand, generally causes genital herpes. However, some genital herpes may be caused by HSV-1 virus, and some oral herpes may be caused by HSV-2. Herpes causes blisters or sores in the mouth or on the genitals and, often with the first infection, a fever and general feeling of illness. HSV is very contagious and can be spread by direct contact with sores and sometimes by contact with the oral and genital areas of people who have chronic HSV infection even when no sores are can be seen.