Shingles (Herpes Zoster): Diagnosis, Rash Features & Complications

Clinical Diagnosis

• Unilateral dermatomal pain/itching/paresthesia → vesicular rash on erythematous base.
• Rash does not cross midline; thoracic (T3–L2) most common.
• Lesions: clusters → pustules → crusts over 2–4 weeks.
• Postherpetic neuralgia (PHN): pain persisting >90 days after rash onset (10–18% of cases).

Special Syndromes

• Herpes zoster ophthalmicus (HZO) – V1 trigeminal; risk of keratitis, uveitis, glaucoma, blindness. Urgent ophthalmology.
• Herpes zoster oticus (Ramsay Hunt) – Geniculate ganglion; facial palsy, vesicles in ear, hearing loss, vertigo.
• Disseminated zoster – >20 lesions outside primary dermatome; immunocompromised.

Laboratory Confirmation

• PCR from vesicle fluid (gold standard).
• DFA on Tzanck smear.
• Viral culture (slow, less sensitive).
• Serology (VZV IgG/IgM) – not for acute diagnosis.

Treatment

• Antiviral (valacyclovir 1g TID × 7d) within 72h of rash.
• Corticosteroids (controversial; may reduce acute pain/PHN in immunocompetent).
• Pain: gabapentinoids, TCAs, opioids if severe.
• Vaccine: RZV (Shingrix) 2 doses ≥50 yrs or ≥19 immunocompromised.