HSV-1 Does NOT Cause Canker Sores
No, HSV-1 causes cold sores (herpes labialis) but does NOT cause canker sores (aphthous ulcers), which are completely different conditions with distinct etiologies.
Critical Distinction Between Cold Sores and Canker Sores
Cold Sores (Herpes Labialis)
- Cold sores are viral infections caused exclusively by HSV-1 (or occasionally HSV-2), presenting as painful vesicular eruptions that form crusts on the lips, perioral area, and oral mucosa 1
- HSV-1 establishes lifelong latency in sensory ganglia (trigeminal ganglia) after primary infection, with the virus persisting in a dormant episomal form within neuronal nuclei 2, 3
- Recurrent cold sores occur when the virus reactivates and travels back along the same nerve pathway, typically appearing at the identical anatomical location as the primary infection 2
- The classic presentation follows a predictable progression: prodrome → erythema → papule → vesicle → pustule → ulceration → crusting 2
Canker Sores (Aphthous Ulcers)
- Canker sores are NOT caused by HSV-1 or any herpes virus - they are non-infectious inflammatory lesions of unknown etiology, likely related to immune dysregulation, nutritional deficiencies, or local trauma
- Unlike cold sores, canker sores appear exclusively inside the mouth on non-keratinized mucosa (inside cheeks, tongue, soft palate) and never on the external lips
- Canker sores are not contagious and do not contain viral particles
Clinical Implications of HSV-1 Cold Sores
Primary HSV-1 Infection
- Primary infection can be asymptomatic or cause severe gingivostomatitis, particularly in children 1, 4
- In children with primary HSV-1 infection, labial herpes (cold sores) may be noted during the acute illness 1
Recurrent Episodes
- Recurrence frequency varies from once every few years to several times monthly 2
- Peak viral titers occur within the first 24 hours after lesion onset, making early episodes highly contagious 2
- Episodes typically last less than 10 days unless complicated by secondary bacterial infection or immunosuppression 2
Triggers for Reactivation
- Menstruation and immunosuppression are documented triggers for viral reactivation from latency 2
- Ultraviolet light exposure can trigger recurrences 5
Common Pitfall to Avoid
The most critical error is confusing cold sores (HSV-1 viral infection) with canker sores (non-viral inflammatory lesions) - this leads to inappropriate antiviral treatment for canker sores, which will not respond to HSV-directed therapy since they are not caused by herpes virus 1. The location is key: cold sores typically appear on the external lips and perioral skin, while canker sores occur only on internal oral mucosa.