What is the treatment for herpes zoster?

Treatment of Herpes Zoster

For immunocompetent adults with herpes zoster, initiate oral valacyclovir 1 gram three times daily for 7 days, starting within 72 hours of rash onset, and continue treatment until all lesions have completely scabbed. 1, 2, 3

First-Line Oral Antiviral Therapy for Uncomplicated Disease

Valacyclovir is the preferred first-line agent due to superior bioavailability, convenient three-times-daily dosing, and proven efficacy in accelerating pain resolution compared to acyclovir. 1, 2, 3, 4

Standard Dosing Regimens:

• Valacyclovir 1000 mg orally three times daily for 7 days (preferred) 1, 2, 3
• Acyclovir 800 mg orally five times daily for 7 days (alternative) 1, 2
• Famciclovir 500 mg orally three times daily for 7 days (alternative) 5, 6

Critical Timing Considerations:

• Treatment should ideally begin within 72 hours of rash onset for maximum efficacy, though benefit may still occur with later initiation. 1, 2, 3, 7
• Continue therapy until all lesions have completely scabbed, not just for an arbitrary 7-day period—this is the key clinical endpoint. 1, 2
• Treatment initiated during prodrome or within 24 hours of lesion onset provides optimal benefit. 1

Comparative Efficacy:

Valacyclovir demonstrates superior pain reduction compared to acyclovir, with median pain duration of 38 days versus 51 days, and reduces postherpetic neuralgia duration (19.3% versus 25.7% with pain persisting at 6 months). 4 Famciclovir reduces median PHN duration by 56-100 days compared to placebo, with greatest benefit in patients ≥50 years. 6

Intravenous Therapy for Severe or Complicated Disease

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

• Disseminated herpes zoster (multi-dermatomal or visceral involvement) 1, 2
• Ophthalmic zoster with suspected CNS involvement 1
• Severely immunocompromised patients (including those on active chemotherapy) 1
• Patients unable to tolerate oral therapy 2

Continue IV therapy until clinical improvement occurs, then switch to oral therapy to complete the treatment course. 2 Monitor renal function closely during IV acyclovir therapy with dose adjustments for renal impairment. 1

Special Population Considerations

Immunocompromised Patients:

• All immunocompromised patients require antiviral treatment regardless of timing. 2
• Consider temporary reduction or discontinuation of immunosuppressive medications in cases of disseminated or invasive disease. 1, 2
• Immunosuppression may be restarted after commencing anti-VZV therapy and resolution of skin vesicles. 2
• High-dose IV acyclovir remains the treatment of choice for severely compromised hosts. 1
• Treatment duration may need extension beyond 7-10 days as lesions continue to develop over longer periods (7-14 days) and heal more slowly. 1

Renal Impairment:

Dose adjustments are mandatory to prevent acute renal failure. 1 For famciclovir with CrCl 20-39 mL/min, reduce to 500 mg every 24 hours. 1

Facial/Ophthalmic Zoster:

Requires urgent treatment due to risk of vision-threatening complications and cranial nerve involvement. 1 Initiate valacyclovir 1 gram three times daily or famciclovir 500 mg three times daily within 72 hours, with particular urgency given complication risks. 1

Acyclovir-Resistant Cases

For suspected acyclovir-resistant herpes zoster, switch to foscarnet 40 mg/kg IV every 8 hours. 1, 2 Acyclovir-resistant isolates are routinely resistant to ganciclovir as well. 2 Monitor renal function and electrolytes (hypocalcemia, hypophosphatemia, hypomagnesemia, hypokalemia) closely. 1

Post-Exposure Prophylaxis

For varicella-susceptible patients exposed to active VZV infection:

• Varicella zoster immunoglobulin (VZIG) within 96 hours of exposure (preferred) 1, 2
• If VZIG unavailable or >96 hours have passed: 7-day course of oral acyclovir beginning 7-10 days after exposure 1, 2

Common Pitfalls to Avoid

• Do not use topical antiviral therapy—it is substantially less effective than systemic therapy. 1
• Do not stop treatment at 7 days if lesions have not completely scabbed—continue until clinical endpoint is reached. 1, 2
• Do not delay treatment waiting for laboratory confirmation in typical presentations—clinical diagnosis is sufficient in immunocompetent patients. 1
• Do not use corticosteroids as monotherapy—they should only be considered as adjunctive therapy in select severe cases, and are contraindicated in immunocompromised patients. 1

Vaccination for Prevention

The recombinant zoster vaccine (Shingrix) is recommended for all adults ≥50 years regardless of prior herpes zoster episodes. 1, 2 Vaccination should ideally occur before initiating immunosuppressive therapies. 1