Treatment of Varicella Zoster Infection
For uncomplicated varicella zoster (chickenpox or shingles), oral acyclovir 800 mg five times daily or valacyclovir 1000 mg three times daily for 7-10 days is the recommended first-line treatment, continuing until all lesions have completely scabbed. 1, 2
Treatment Algorithm Based on Disease Severity and Host Status
Immunocompetent Patients with Uncomplicated Disease
Oral antiviral therapy is the standard of care:
- Valacyclovir 1000 mg three times daily for 7 days is preferred due to superior bioavailability and less frequent dosing compared to acyclovir 1, 3
- Acyclovir 800 mg five times daily for 7-10 days remains effective but requires more frequent dosing 1, 4
- Famciclovir 500 mg three times daily for 7 days offers comparable efficacy to valacyclovir 1, 3
Critical timing consideration: Treatment must be initiated within 72 hours of rash onset for optimal efficacy in reducing acute pain, accelerating lesion healing, and preventing postherpetic neuralgia 1. However, treatment initiated beyond 72 hours may still provide benefit 3.
Treatment endpoint: Continue antiviral therapy until all lesions have completely scabbed, not just for an arbitrary 7-day period—this is the key clinical endpoint 1, 2.
Immunocompromised Patients or Disseminated Disease
Intravenous acyclovir is mandatory for high-risk presentations:
- IV acyclovir 10 mg/kg every 8 hours is the treatment of choice for disseminated VZV, severe disease, or immunocompromised hosts 1, 5, 2
- Continue IV therapy for a minimum of 7-10 days and until clinical resolution is attained (all lesions completely scabbed) 1, 5
- Consider temporary reduction or discontinuation of immunosuppressive medications while maintaining antiviral therapy 1, 5, 2
- Switch to oral therapy only after clinical response is observed 2
High-risk populations requiring IV therapy include: patients on chemotherapy, organ transplant recipients with disseminated disease, HIV-infected patients with severe disease, and those with visceral involvement or CNS complications 1, 5, 2.
Special Clinical Scenarios
Facial/ophthalmic zoster:
- Requires urgent treatment with oral valacyclovir 1000 mg three times daily or famciclovir 500 mg three times daily, continuing until all lesions have scabbed 1
- Consider IV acyclovir for complicated facial zoster with suspected CNS involvement or severe ophthalmic disease 1
Chickenpox in children (ages 2-18 years):
- Valacyclovir oral suspension 20 mg/kg three times daily for 5 days (not to exceed 1000 mg three times daily) 6
- Treatment is particularly recommended for adolescents and young adults 4
Pregnant women exposed to VZV:
- Varicella zoster immune globulin (VZIG) within 96 hours of exposure 7, 2
- If VZIG unavailable or >96 hours post-exposure, oral acyclovir 7-day course starting 7-10 days after exposure 7, 2
Critical Monitoring and Dose Adjustments
Renal function monitoring is essential:
- Monitor renal function at initiation and once or twice weekly during IV acyclovir treatment 1
- Adjust acyclovir dose for renal impairment to prevent nephrotoxicity 5
- Ensure adequate hydration to prevent acyclovir-induced crystalline nephropathy 5, 8
For acyclovir-resistant cases:
- Switch to foscarnet 40 mg/kg IV every 8 hours 1, 2
- Suspect resistance if lesions fail to resolve within 7-10 days despite treatment 1
Common Pitfalls to Avoid
Do not use inadequate dosing: The dose of 400 mg acyclovir three times daily is only appropriate for genital herpes or HSV suppression, not for varicella zoster infections 1.
Do not rely on topical antivirals: Topical acyclovir is substantially less effective than systemic therapy and is not recommended 1.
Do not use oral antivirals for disseminated disease: This is a critical error—IV acyclovir is mandatory for disseminated or potentially disseminated VZV 5.
Do not delay treatment: Initiate IV acyclovir based on clinical suspicion alone without waiting for confirmatory testing in suspected disseminated disease 5.
Do not stop treatment prematurely: Continue therapy until all lesions have completely scabbed, which may extend beyond 7-10 days in immunocompromised patients who develop new lesions for 7-14 days and heal more slowly 1, 2.
Prevention Strategies
Post-exposure prophylaxis:
- VZIG 5 vials (1.25 mL each) intramuscularly within 96 hours of substantial exposure for VZV-susceptible patients 7, 2
- If VZIG unavailable or >96 hours post-exposure: oral acyclovir for 7 days starting 7-10 days after exposure 7, 2
Vaccination: