Is herpes contagious?

Dr Rosemary Leonard Cold sores, also known as fever blisters, are caused by two strains of the herpes simplex virus. Herpes simplex virus type 1 (HSV-1) is the main cause of oral and facial cold sores, although HSV-2, which tends to affect the genitals, can also affect the mouth and face if it is transmitted there. The cold sore virus is most commonly passed on through kissing (or oral sex) when a blister is present. For more information on herpes, go to [https://patient.info/health/viral-skin-infections-leaflet/features/surprising-facts-about-cold-sores-everyone-should-know](https://patient.info/health/viral-skin-infections-leaflet/features/surprising-facts-about-cold-sores-everyone-should-know)