Fever blisters, also known as cold sores, are caused by an infection with the herpes simplex virus, primarily herpes simplex virus type 1 (HSV-1). This virus lies dormant in nerve cells and can be reactivated periodically, leading to outbreaks of fever blisters. Common triggers for reactivation include fatigue, stress, physical or emotional trauma, illness or fever, sun exposure, hormonal changes, and immune system changes. Fever blisters typically appear as red, swollen, sore blisters around the mouth or other facial areas and can release fluid before scabbing over. The virus is contagious, especially when blisters are present, but can spread even with no visible sores.
Causes and Triggers
- Infection with herpes simplex virus type 1 (HSV-1)
- Reactivation triggered by:
- Fatigue or stress
- Illness or fever
- Sun exposure or skin injury
- Hormonal changes (e.g., menstruation)
- Immune system changes or suppression
Contagion and Recurrence
- HSV-1 is very common, with a large portion of the population infected, though many never show symptoms.
- Once infected, the virus remains in the body and can cause recurrent outbreaks.
- The blisters are contagious through close contact and shared items like eating utensils or towels.
Related Conditions
- Fever blisters differ from canker sores, which are not caused by a virus and are not contagious.
This understanding highlights how fever blisters are caused by a viral infection and are influenced by various physiological and environmental factors.
