What is the recommended treatment for herpes zoster?

Treatment of Herpes Zoster

For uncomplicated herpes zoster, initiate oral valacyclovir 1 gram three times daily for 7 days within 72 hours of rash onset, or alternatively famciclovir 500 mg every 8 hours for 7 days. 1, 2

First-Line Oral Antiviral Therapy

Valacyclovir is the preferred first-line agent:

• Dosing: 1 gram orally three times daily for 7 days 1, 3
• Advantages: Superior bioavailability compared to acyclovir, more convenient dosing schedule, and proven efficacy in accelerating pain resolution 4
• Timing: Most effective when initiated within 72 hours of rash onset, though treatment beyond this window still provides benefit 1, 5

Famciclovir is an equally effective alternative:

• Dosing: 500 mg orally every 8 hours for 7 days 1, 2
• Advantages: May provide superior acute pain relief compared to valacyclovir, particularly in patients ≥50 years old 6
• Evidence: Reduces median duration of postherpetic neuralgia by 3.5 months in patients ≥50 years 7

Acyclovir remains a viable option when other agents are unavailable:

• Dosing: 800 mg orally five times daily for 7 days 1, 3
• Disadvantage: Requires more frequent dosing (five times daily), which may reduce adherence 1

Treatment Duration and Endpoints

Continue antiviral therapy until all lesions have completely scabbed, not just for an arbitrary 7-day period. 1, 3

• In immunocompetent patients, lesions typically scab within 7-10 days 3
• If new lesions continue forming or healing is incomplete beyond 7 days, extend treatment duration 1
• The key clinical endpoint is complete scabbing of all lesions, not calendar days 1

Severe or Complicated Disease Requiring IV Therapy

Switch to intravenous acyclovir 5-10 mg/kg every 8 hours for: 1, 3

• Disseminated herpes zoster (multi-dermatomal involvement)
• Visceral organ involvement
• Ophthalmic zoster with suspected CNS complications
• Severely immunocompromised patients
• Patients unable to tolerate oral therapy

Continue IV therapy until clinical improvement occurs, then switch to oral therapy to complete the treatment course. 1

Special Populations

Immunocompromised Patients

• All immunocompromised patients require antiviral treatment regardless of timing 1
• Consider IV acyclovir 10 mg/kg every 8 hours for severely immunocompromised hosts 1
• May require treatment extension beyond 7-10 days as lesions develop over 7-14 days and heal more slowly 3
• Temporarily reduce or discontinue immunosuppressive therapy in cases of disseminated VZV infection 1, 3
• Monitor closely for dissemination and visceral complications 1

HIV-Infected Patients

• Dosing: Famciclovir 500 mg twice daily for 7 days for recurrent orolabial or genital herpes 1, 2
• Higher oral doses may be needed (up to 800 mg acyclovir 5-6 times daily) 3
• Consider long-term acyclovir prophylaxis (400 mg 2-3 times daily) 3

Renal Impairment

Dose adjustments are mandatory to prevent acute renal failure: 3, 2

• Famciclovir for herpes zoster:
  • CrCl ≥60 mL/min: 500 mg every 8 hours
  • CrCl 40-59 mL/min: 500 mg every 12 hours
  • CrCl 20-39 mL/min: 500 mg every 24 hours
  • CrCl <20 mL/min: 250 mg every 24 hours
  • Hemodialysis: 250 mg following each dialysis 2

Acyclovir-Resistant Cases

For suspected acyclovir-resistant herpes zoster, switch to foscarnet 40 mg/kg IV every 8 hours. 1, 3

• Acyclovir-resistant isolates are routinely resistant to ganciclovir as well 1
• Requires close monitoring of renal function and electrolytes (hypocalcemia, hypophosphatemia, hypomagnesemia, hypokalemia) 1

Adjunctive Immunosuppression Management

• Temporarily reduce immunosuppressive medications in cases of disseminated or invasive herpes zoster 1, 3
• Restart immunosuppression after commencing anti-VZV therapy and after skin vesicles have resolved 1

Post-Exposure Prophylaxis

For varicella-susceptible patients exposed to active VZV infection: 1, 3

• Preferred: Varicella zoster immunoglobulin (VZIG) within 96 hours of exposure
• Alternative (if VZIG unavailable or >96 hours post-exposure): Oral acyclovir for 7 days beginning 7-10 days after exposure

Critical Pitfalls to Avoid

• Do not rely on topical antiviral therapy - it is substantially less effective than systemic therapy and is not recommended 3
• Do not underdose acyclovir - 400 mg TDS is only appropriate for genital herpes or HSV suppression, not for shingles 3
• Do not stop treatment at 7 days if lesions remain active - continue until complete scabbing occurs 1, 3
• Do not delay treatment in immunocompromised patients - they require immediate antiviral therapy regardless of timing 1
• Monitor renal function closely during IV acyclovir therapy with dose adjustments as needed 3

Prevention

The recombinant zoster vaccine (Shingrix) is recommended for all adults aged ≥50 years, regardless of prior herpes zoster episodes. 1, 3

• Ideally administer before initiating immunosuppressive therapies 3
• Can be considered after recovery to prevent future episodes 3