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Cold sores (herpes labialis)
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Herpes labialis, what a lot of people call cold sores or fever blisters, is an infection with the herpes simplex virus, usually type 1. It shows up as painful, fluid-filled sores around the lips, and it's contagious.
The interesting part is what happens between one cold sore and the next. After the infection, the virus doesn't go away. It stays latent, which means dormant, mostly inside the neurons of the trigeminal ganglion, a small cluster of nerve cells. Think of a lamp that's switched off but still plugged in. It isn't giving off any light, but it's there, and something can turn it back on. That's reactivation: the virus wakes up and travels to the skin. Things that can wake it up include stress, sunlight, or trauma, which here just means an injury or a blow.
A recurrence, meaning the cold sore coming back, usually gives a warning before you can see anything: first the spot burns or itches. Then vesicles appear. These are tiny fluid-filled blisters that break open and crust over. And the sore always comes back in the same area.
In brief
Herpes labialis, better known as cold sores or fever blisters, is a contagious infection with the herpes simplex virus, usually type 1, that causes painful, fluid-filled sores around the lips.
After infection, the virus lies latent, mainly in the neurons of the trigeminal ganglion; sometimes it reactivates in response to triggers such as stress, sunlight, or trauma and travels to the skin.
Recurrences are usually heralded by burning or itching; then vesicles form, break open, and crust over, always in the same area.
Sources (3)
- National Institute of Dental and Craniofacial Research, National Institutes of HealthFever Blisters & Canker Sores
- National Center for Biotechnology Information, StatPearls PublishingHerpetic Gingivostomatitis, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingViral Infections of the Oral Mucosa, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated