Causes of Fever Blisters
While both types of herpes simplex viruses are causes of fever blisters, most cases are caused by the herpes simplex type 1 virus. The virus is generally spread through direct skin-to-skin or mucous membrane contact, but sharing items that have come into contact with a blister can also transmit the virus. It is believed that fever blisters tend to return because of factors such as fever, stress, and fatigue.
Fever blisters are one of the most common conditions of the mouth. Also known as cold sores (and known medically as herpes labialis), fever blisters are caused by a contagious virus called the herpes simplex virus.
There are two types of herpes simplex viruses:
- Herpes simplex type 1 (HSV-1)
- Herpes simplex type 2 (HSV-2).
Most cases of fever blisters are caused by HSV-1. In fact, more than 95 percent of recurrent fever blister outbreaks are caused by HSV-1. Most people infected with the HSV-1 virus usually become infected before they are 10 years old.
One way that the herpes simplex virus is spread is by direct skin-to-skin or mucous membrane contact. For example, kissing a person with a fever blister is probably the most common way that the virus is spread. The virus may also be spread by sharing things such as utensils, napkins, drinks, towels, or razors that have come in contact with a fever blister.
Children often become infected through contact with parents, siblings, or other close relatives who have fever blisters. A child can spread the virus by rubbing his or her fever blister and then touching other children.
About 10 percent of oral herpes infections in adults result from oral sex with a person who has active genital herpes. These infections, however, usually do not result in repeat bouts of fever blisters.