What Causes Cold Sores at the Corners of the Mouth?

Herpes is classified into two main types: herpes simplex and herpes zoster. Herpes simplex is caused by the herpes simplex virus (HSV), whereas herpes zoster results from the varicella-zoster virus (VZV). After infection, these viruses can remain dormant for prolonged periods within nerve roots. When host immunity declines, the viruses reactivate and replicate extensively, leading to clinical manifestations. So, what causes herpes lesions at the corner of the mouth? Below is a detailed explanation.

Causes of Herpes Lesions at the Corner of the Mouth

1. Viral Infection

Herpes lesions at the corner of the mouth result from infection with herpesviruses—the fundamental cause of such lesions. Herpes viruses are categorized as either herpes simplex virus (HSV) or varicella-zoster virus (VZV). Upon entering the human body, these viruses impair sensory nerve function and establish lifelong latency within dorsal root ganglia. They may also travel along peripheral nerves to reach the epidermis, where they undergo widespread replication. Subsequent reactivation—triggered by various factors—leads to symptomatic herpes outbreaks.

2. Immune Suppression

Reduced immune function serves as a key trigger for herpes lesions at the corner of the mouth. Following primary infection, herpesviruses persist latently in nerve roots. A decline in host immunity—such as during physical trauma, fatigue, upper respiratory infections (e.g., common cold), malignancy, immunologic disorders, or the female menstrual period—can prompt viral reactivation and prolific replication, resulting in clinical symptoms.

The above outlines the etiology of herpes. Herpes lesions at the corner of the mouth are fundamentally caused by herpesvirus infection, while immune suppression acts as a precipitating factor. Additionally, herpes is contagious—primarily transmitted via direct contact, but also indirectly through saliva-contaminated utensils. We hope this information proves helpful.