Key Facts

Herpes zoster (shingles) results from reactivation of latent VZV. It is common, affecting approximately 1 in 3 people during their lifetime. The risk increases with age and immunosuppression. Early antiviral treatment and vaccination are the key management strategies.

Epidemiology

• Lifetime risk: ~30%
• Incidence increases with age: ~1% per year in >80s
• UK: ~50,000 cases/year in >70s
• Recurrence: ~5% over a lifetime (higher in immunosuppressed)
• PHN: ~10–15% overall; ~20% in >60 years; ~30% in >80 years

Aetiology

• VZV (human herpesvirus 3): primary infection → varicella (chickenpox) → virus establishes latency in dorsal root ganglia
• Reactivation triggers: declining cell-mediated immunity (ageing), immunosuppression (HIV, chemotherapy, transplant, corticosteroids), stress, trauma
• Reactivation → viral replication in ganglion → travels along sensory nerve → dermatomal rash

Pathophysiology

• VZV reactivates in dorsal root ganglion → anterograde axonal transport to skin
• Viral replication in epidermis → vesicle formation
• Neural inflammation and damage → acute pain
• Persistent neural damage → post-herpetic neuralgia (aberrant nerve repair, central sensitisation)
• Typically involves a single dermatome; dissemination (≥3 dermatomes) suggests immunosuppression

Prodromal Phase (2–4 Days Before Rash)

• Pain, burning, tingling in affected dermatome
• May be mistaken for cardiac, pleural, or abdominal pain depending on dermatome
• Malaise, headache, low-grade fever

Active Phase

• Unilateral vesicular rash in a dermatomal distribution - does NOT cross midline
• Crops of vesicles on an erythematous base
• Vesicles become pustular → crust over 7–10 days → resolve over 2–4 weeks
• Thoracic dermatomes: most common (50–70%)
• Trigeminal (V1): herpes zoster ophthalmicus (~10–15%)
• Sacral (S2–S4): may cause urinary retention

Herpes Zoster Ophthalmicus (V1)

• Hutchinson's sign: vesicles on tip/side of nose (nasociliary nerve involvement) - predicts ocular involvement (~75%)
• Complications: keratitis, anterior uveitis, secondary glaucoma, optic neuritis
• Requires URGENT ophthalmology assessment

Ramsay Hunt Syndrome (Geniculate Ganglion)

• Ear pain + ipsilateral facial nerve palsy (LMN) + vesicles in ear canal/pinna
• May have hearing loss, tinnitus, vertigo
• Caused by VZV reactivation in geniculate ganglion

Red Flags

• Disseminated zoster (≥3 dermatomes): suggests immunosuppression - investigate
• Herpes zoster ophthalmicus: urgent ophthalmology
• Ramsay Hunt syndrome: urgent ENT/neurology
• Motor weakness: rare; anterior horn cell involvement
• Immunosuppressed with zoster: risk of visceral dissemination

Bedside

• Clinical diagnosis: characteristic dermatomal vesicular rash - usually no investigations needed
• Viral swab (PCR): vesicle fluid - VZV PCR confirms diagnosis if atypical or immunosuppressed

Bloods

• Not routinely required for uncomplicated zoster
• FBC, U&Es: if considering IV aciclovir (renal dosing)
• HIV test: consider if young patient, disseminated, or recurrent zoster
• VZV serology: IgM/IgG - rarely needed; PCR is preferred

Imaging

• Not required for uncomplicated zoster
• MRI brain: if CNS complications suspected (encephalitis, vasculopathy)

Special Tests

• Ophthalmology slit-lamp examination: if zoster ophthalmicus - assess for keratitis, uveitis
• Audiometry: if Ramsay Hunt syndrome - assess hearing loss

Non-Pharmacological

• Wound care: keep rash clean and dry; calamine lotion for symptomatic relief
• Avoid contact with non-immune individuals (pregnant women, neonates, immunosuppressed) until all vesicles have crusted
• NOT notifiable but advise on infectivity (VZV can cause chickenpox in non-immune contacts)

Pharmacological - Antivirals

• Start within 72 hours of rash onset (or later if ongoing vesicle formation, immunosuppressed, or zoster ophthalmicus)
• Aciclovir 800 mg 5 times daily for 7 days: standard first-line
• Valaciclovir 1 g TDS for 7 days: better bioavailability, simpler regimen - increasingly preferred
• Famciclovir 500 mg TDS for 7 days: alternative
• IV aciclovir 10 mg/kg TDS for 7–14 days: for immunosuppressed, disseminated, or CNS involvement (ensure adequate hydration - risk of crystalline nephropathy)

Pain Management

Acute pain:

• Paracetamol 1 g QDS and/or ibuprofen 400 mg TDS: first-line
• Codeine 30–60 mg QDS: if insufficient
• Amitriptyline 10–25 mg ON: if neuropathic component; also reduces PHN risk

Post-Herpetic Neuralgia (pain >90 days):

• Amitriptyline 10–75 mg ON: first-line (NICE CG173)
• Gabapentin 300 mg OD → titrate to 600 mg TDS: first-line alternative
• Pregabalin 75 mg BD → titrate to 300 mg BD: alternative
• Topical capsaicin 0.075% cream QDS: adjunct for localised PHN
• Topical lidocaine 5% plaster: localised PHN
• Pain clinic referral: refractory PHN

Vaccination

• Shingrix (recombinant VZV glycoprotein E): offered at age 65 in UK; 2 doses (0 and 2 months); >90% efficacy; non-live - safe in immunosuppressed
• Replaced Zostavax (live vaccine) in UK programme

Referral Criteria

• Ophthalmology (same-day): herpes zoster ophthalmicus, Hutchinson's sign
• ENT: Ramsay Hunt syndrome
• Hospital admission: disseminated zoster, immunosuppressed requiring IV aciclovir, CNS complications
• Pain clinic: refractory post-herpetic neuralgia

• Uncomplicated zoster: rash resolves in 2–4 weeks; most patients recover fully
• PHN: most common complication; risk increases with age - ~10–15% overall, ~30% in >80 years; most cases resolve within 1 year
• Zoster ophthalmicus: risk of permanent visual loss without treatment; good prognosis with prompt antiviral and ophthalmology input
• Ramsay Hunt syndrome: facial nerve recovery ~50–70% (worse than Bell's palsy)
• Disseminated zoster: significant morbidity/mortality in immunosuppressed
• Recurrence: ~5% lifetime; more common in immunosuppressed

Herpes Zoster Complications

PHN Treatment Ladder