What is the recommended treatment for an adult patient presenting with Herpes zoster?

Treatment of Herpes Zoster in Adults

Initiate oral valacyclovir 1000 mg three times daily for 7-10 days within 72 hours of rash onset, continuing treatment until all lesions have completely scabbed. 1, 2

First-Line Oral Antiviral Therapy

Valacyclovir is the preferred first-line agent due to superior bioavailability and less frequent dosing compared to acyclovir, which significantly improves patient adherence. 1, 2

• Valacyclovir 1000 mg three times daily for 7-10 days is the recommended regimen 1, 2, 3
• Acyclovir 800 mg five times daily for 7-10 days remains an effective alternative, though requires more frequent dosing 1, 2
• Famciclovir 500 mg three times daily for 7-10 days offers comparable efficacy with convenient dosing 1

The critical distinction between these agents is pharmacokinetic: valacyclovir achieves 3-5 fold higher bioavailability than acyclovir, allowing less frequent administration while maintaining equivalent or superior clinical outcomes. 4, 5

Critical Treatment Timing and Endpoint

• 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, 2, 3
• Do not discontinue antiviral therapy at exactly 7 days if lesions are still forming or have not completely scabbed - the key clinical endpoint is complete scabbing of all lesions, not an arbitrary calendar duration 1, 2, 6

This is a common pitfall: clinicians may stop treatment after 7 days even when active vesiculation persists, which is inadequate for VZV infection. 6

When to Escalate to Intravenous Therapy

Switch to intravenous acyclovir 10 mg/kg every 8 hours if any of the following occur: 1, 2, 6

• Disseminated herpes zoster (multi-dermatomal or visceral involvement)
• Suspected CNS complications
• Severe immunocompromise (HIV with low CD4 count, active chemotherapy, solid organ transplant)
• Complicated ophthalmic zoster with suspected ocular involvement
• Inability to take oral medications
• Failure to respond to oral therapy within 7-10 days

Continue IV therapy for a minimum of 7-10 days and until clinical resolution is attained, then consider switching to oral therapy to complete the treatment course. 2

Special Populations Requiring Modified Approach

Immunocompromised patients:

• All immunocompromised patients with herpes zoster require antiviral treatment regardless of timing from rash onset 2
• For uncomplicated herpes zoster in stable immunocompromised patients (kidney transplant recipients, controlled HIV), use oral valacyclovir or acyclovir with close monitoring for dissemination 2, 6
• Consider temporary reduction in immunosuppressive medications for disseminated or invasive disease 6

Renal impairment:

• Monitor renal function closely and adjust doses accordingly - acyclovir and valacyclovir require dose reduction based on creatinine clearance 6

Management of Acyclovir-Resistant Cases

If lesions fail to begin resolving within 7-10 days despite appropriate therapy:

• Suspect acyclovir resistance and obtain viral culture with susceptibility testing 1, 6
• Switch to foscarnet 40 mg/kg IV every 8 hours until clinical resolution 6
• All acyclovir-resistant strains are also resistant to valacyclovir, and most are resistant to famciclovir 6

Adjunctive Considerations

Corticosteroids:

• Oral corticosteroids may provide modest benefits in reducing acute pain but carry significant risks (infections, hypertension, myopathy, glaucoma, osteopenia) 6
• Avoid corticosteroids in immunocompromised patients as they can increase risk of disseminated infection 1, 6

Topical therapy:

• Topical antivirals are substantially less effective than systemic therapy and are not recommended 6

Prevention and Vaccination

• The recombinant zoster vaccine (Shingrix) is recommended for all adults aged 50 years and older regardless of prior herpes zoster episodes, administered in 2 doses 2-6 months apart 1, 2, 6
• Shingrix reduces shingles incidence by approximately 90% even in the oldest age groups 1
• Vaccination can be administered after recovery from acute herpes zoster to prevent future episodes 6

Infection Control

Patients with active herpes zoster should avoid contact with susceptible individuals (pregnant women who are varicella-seronegative, immunocompromised persons, infants, those without chickenpox history or vaccination) until all lesions have crusted, as the virus can be transmitted and cause varicella in susceptible contacts. 1, 2, 6

Monitoring Parameters

• Monitor renal function if using acyclovir or valacyclovir, particularly in elderly patients or those with baseline renal impairment 1
• Assess for complete scabbing of all lesions as the treatment endpoint 1, 2
• Evaluate for signs of dissemination, CNS involvement, or treatment failure requiring escalation to IV therapy 1, 2