Shingles vs. Cold Sores: Different Viruses, Different Diseases

Two Herpesviruses, Distinct Clinical Entities

Comparison

Feature	Shingles (Herpes Zoster)	Cold Sores (Herpes Labialis)
Virus	Varicella-Zoster Virus (VZV / HHV-3)	Herpes Simplex Virus Type 1 (HSV-1 / HHV-1)
Primary Infection	Chickenpox (varicella) – usually childhood	Oral herpes – often asymptomatic or gingivostomatitis
Latency Site	Dorsal root ganglia (sensory nerves)	Trigeminal ganglion
Reactivation Trigger	Age, immunosuppression, stress, trauma	Sun, stress, fever, trauma, menses
Rash Distribution	Unilateral dermatome (thoracic > trigeminal)	Perioral, lips, vermillion border
Rash Appearance	Clustered vesicles on erythematous base → crust	Clustered vesicles on lip border → crust
Pain	Severe, neuropathic (burning, stabbing), often precedes rash	Mild tingling/burning (prodrome)
Complications	PHN (postherpetic neuralgia), ophthalmicus, Ramsay Hunt, meningitis	Recurrence, ocular HSV (keratitis), encephalitis (rare)
Transmission	Vesicle fluid → varicella in susceptible (not zoster)	Saliva, vesicle fluid → HSV-1 (oral/genital)
Vaccine	Shingrix (RZV) – 2 doses ≥50y or ≥19y immunocompromised. >90% efficacy.	None for HSV-1. Valacyclovir suppression reduces outbreaks.
Antivirals	Valacyclovir 1g TID × 7d (start ≤72h)	Valacyclovir 2g BID × 1d (episodic) or daily suppression

Key Clarification

You cannot get shingles from someone with cold sores. You can get chickenpox (if never immune) from shingles vesicle fluid. Cold sores transmit HSV-1.