Herpes Zoster
Also known as: Shingles
Reactivation of latent VZV from dorsal root/cranial nerve ganglia, typically decades after primary varicella, associated with age related or acquired immune decline.
Prodrome: dermatomal pain/burning/tingling 1-5 days before rash.
Rash: unilateral, dermatomal (does not cross midline), erythematous base with grouped vesicles → pustules → crusting over 7-10 days, healing over 2-4 weeks.
Thoracic dermatomes most common.
Ophthalmic zoster (V1): vision-threatening; Hutchinson's sign (nose-tip vesicles predicts ocular involvement) ; same-day ophthalmology
Ramsay Hunt syndrome: facial palsy + ear pain + vesicles in ear canal (see Bell's Palsy entry)
Complications: postherpetic neuralgia (>90 days, most common, increases with age), secondary bacterial infection, disseminated zoster (immunosuppression, resembles varicella), motor zoster (rare)
Clinical, characteristic dermatomal vesicular rash. PCR of vesicular fluid if diagnostic uncertainty/atypical/immunocompromised.
Differentials: HSV, contact dermatitis, impetigo, insect bites ; dermatomal unilateral distribution with prodromal pain is the key clue.
Antiviral therapy; most effective within 72h of rash onset: valaciclovir 1g PO tds × 7 days, or famciclovir 500mg PO tds × 7 days, or aciclovir 800mg PO 5×/day × 7-10 days
IV aciclovir 10mg/kg 8-hourly: immunocompromised, disseminated, ophthalmic zoster with significant involvement
Analgesia: paracetamol/NSAIDs; neuropathic agents (gabapentin, pregabalin, amitriptyline) if significant neuropathic component
Ophthalmic zoster: urgent same-day ophthalmology
Postherpetic neuralgia: gabapentin (titrate to 900-3600mg/day), pregabalin, or TCAs ; first-line; topical lidocaine/capsaicin for localized pain
Secondary bacterial infection: flucloxacillin
Contagious via vesicular fluid until crusted; avoid contact with non-immune/pregnant/immunocompromised individuals
Prevention: zoster vaccine (recombinant, e.g., Shingrix, 2-dose) for adults ≥50 ; reduces incidence and postherpetic neuralgia, safe in immunocompromised.
Referral: ophthalmology urgently for ophthalmic zoster; ENT/neurology for Ramsay Hunt; pain specialist for refractory PHN.
