Cold Sores (Oral Herpes): Triggers, Treatment & Prevention

Cold sores (herpes labialis) are caused by herpes simplex virus type 1 (HSV-1). Affects ~67% of global population <50 years. Recurrent, self-limited.

Pathogenesis

• Primary infection: often asymptomatic childhood; can cause gingivostomatitis.
• Virus establishes latency in trigeminal ganglion.
• Reactivation triggers: stress, UV light, fever, trauma, hormonal changes, immunosuppression.

Clinical Course

1. Prodrome: tingling, burning, itching (6–24h).
2. Vesicles: clustered on lip vermillion border.
3. Ulceration: rupture → painful erosions.
4. Crusting: honey-colored scab.
5. Healing: 7–10 days (primary longer).

Treatment Options

• Topical Antivirals: Acyclovir 5% cream, penciclovir 1% cream – apply 5x/day at prodrome. Modest benefit (shortens 0.5–1 day).
• Oral Antivirals: Valacyclovir 2g BID ×1 day (or 1g BID ×5 days), famciclovir 1500 mg single dose, acyclovir 400 mg 5x/day ×5 days. More effective if started early.
• Suppressive Therapy: Daily valacyclovir 500–1000 mg for frequent recurrences (≥6/yr).
• Symptomatic: NSAIDs, topical anesthetics (lidocaine/benzocaine), cold compresses, lysine (weak evidence).

Prevention & Transmission Reduction

• Avoid kissing/contact during active lesion.
• Don't share utensils, towels, lip balm.
• Sunscreen (SPF 30+) on lips if UV trigger.
• Stress management, adequate sleep.
• Consider suppressive therapy if frequent/severe.

HSV-1 vs. HSV-2

HSV-1 = primarily oral; HSV-2 = primarily genital. But both can infect either site via oral-genital contact.

When to See a Clinician

• Eye involvement (herpes keratitis – sight-threatening).
• Lesions >2 weeks, spreading, immunosuppressed.
• Frequent/severe recurrences.
• Neonatal exposure (high risk).

No cure, but effective management reduces frequency, severity, and transmission.