What is the recommended treatment for pain after herpes zoster diagnosis?

Treatment of Pain After Herpes Zoster Diagnosis

Acute Phase Antiviral Therapy

For acute herpes zoster, initiate valacyclovir 1 gram orally three times daily for 7 days within 72 hours of rash onset to reduce pain duration and prevent post-herpetic neuralgia. 1

• Alternative regimen: acyclovir 800 mg orally five times daily for 7 days if valacyclovir is unavailable 1
• Valacyclovir significantly accelerates resolution of herpes zoster-associated pain compared to acyclovir (median 38 days vs 51 days, p=0.001) and reduces the proportion of patients with pain persisting at 6 months (19.3% vs 25.7%) 2
• Treatment initiated beyond 72 hours may still provide benefit; short-course acyclovir therapy (4 days) shows similar efficacy in patients treated after 72 hours compared to those treated earlier 3
• For severe or disseminated disease requiring hospitalization: intravenous acyclovir 5-10 mg/kg every 8 hours until clinical improvement, then switch to oral therapy 1

Post-Herpetic Neuralgia Management

First-Line Pharmacologic Treatment

Gabapentin is the first-line oral pharmacological treatment for post-herpetic neuralgia, titrated to 2400 mg per day in divided doses. 4

• Gabapentin demonstrates efficacy with a number needed to treat (NNT) of 4.39 for post-herpetic neuralgia 4
• Pain reduction is typically seen by Week 1 and maintained through treatment 5
• Common side effect: somnolence reported in 80% of patients, though this may improve sleep scores 4

Second-Line Options if Inadequate Response to Gabapentin

• Pregabalin for post-herpetic neuralgia (NNT = 4.93) 4
• Tricyclic antidepressants (NNT = 2.64) 4
• Serotonin-norepinephrine reuptake inhibitors based on general population effectiveness 4

Topical Therapies

Capsaicin 8% dermal patch is recommended as topical treatment, providing pain relief for at least 12 weeks after a single 30-minute application. 4

• Pre-treat with 4% lidocaine for 60 minutes before capsaicin application to minimize erythema and pain 4
• Topical lidocaine patches also show efficacy (NNT = 2) 4

Non-Pharmacologic Interventions

• Cognitive behavioral therapy for chronic pain management 4
• Physical and occupational therapy for persistent pain 4
• Hypnosis specifically for neuropathic pain 4

Opioid Considerations

Opioids should not be prescribed as first-line agents for long-term management of post-herpetic neuralgia. 4

• May consider time-limited trial only after failure of first-line therapies in patients with moderate to severe pain 4
• Specific opioids showing efficacy in post-herpetic neuralgia include oxycodone, extended-release morphine, and methadone (NNT = 2.67) 4

Critical Timing Considerations

• Antiviral therapy is most effective when initiated within 72 hours of rash onset 1
• Pain reduction during acute phase is greater with early treatment, though this does not necessarily prevent post-herpetic neuralgia development 6
• Continue antiviral treatment beyond 7 days if new lesions continue forming or healing is incomplete 1

Common Pitfall

The addition of corticosteroids (prednisolone 40 mg tapered over 3 weeks) to acyclovir provides only slight benefits in acute pain reduction and does not reduce the frequency of post-herpetic neuralgia, while increasing adverse events 6. Therefore, routine corticosteroid use is not recommended.