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Post Herpetic Neuralgia (PHN) is the most common complication of Herpes Zoster-Varicella
(HZV). Pain is sustained for at least 90 days after the rash. It occurs in approximately 20% of
patients with HZV & 80% of cases occur in patients 50 years or older.

Photos of Oro-Facial Herpes Zoster-Varicella Infections

What is Post-Herpetic Neuralgia (PHN)?

PHN is caused by nerve damage secondary to an inflammatory response induced by viral replication within a nerve.

PHN pain is typically discretely localised, intermittent, chronic & sufficiently intense to interfere with sleep & other normal daily activities. Additionally, the pain may have an itching, burning, sharp, stabbing / throbbing quality. PMH may be associated with allodynia / hyperalgesia.

Aggravating factors include light touch, such as the touch of clothing / standing in a shower.

Relieving factors may include barriers to touch.

Risk Factors

These include:

  • Older age
  • Severe prodrome / rash
  • Severe acute HZV pain
  • Ophthalmic involvement
  • Immunosuppression
  • Chronic conditions such as Diabetes Mellitus & Lupus
  • Symptoms of allodynia

How is Post-Herpetic Neuralgia treated?

Pain-management strategies should focus on symptom-control.

Although some patients have complete resolution of symptoms after several years, others have to continue using medications indefinitely.

  • Capsaicin cream 0.075% cream 3 – 4x daily
  • Lidocaine medicated plasters 5% to use for 12 hours & rest for 12 hours
  • Antidepressants (Nortryptiline 10 – 125mg / day & Duloxetine 60 – 120mg / day)
  • Anticonvulsants (Gabapentin 300 – 600mg mg TDS & Pregabalin 150 – 300mg / day)
  • Tramadol 50 – 100 mg 4 – 6 hourly
  • Amantidine 100 mg BD for 2/52 – to be continued for another 2/52 if necessary

Referral to specialist clinics (Oral Medicine & Oro-Facial Pain clinics).

Management of Post-Herpetic Neuralgia

Differential Diagnosis:

The differential diagnosis includes:

  • PHN
  • Impetigo
  • Candidiasis
  • Contact dermatitis
  • Insect bites
  • Auto-Immune blistering diseases
  • Dermatitis herpetiformis
  • Drug-related eruptions