Educational Content: This article is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.
Definition of Human herpesvirus 1 (HHV-1)
Medically reviewed by Min Clinic Staff | Updated: January 2026
Human herpesvirus 1 (HHV-1): A herpes virus that causes cold sores and fever blisters in and around the mouth. Here is a depiction of a typical fever blister caused by HHV-1:
In rare cases, as when the immune system is severely compromised, this virus can cause infection of the brain (encephalitis). HHV-1 is also known as herpes simplex type .
