What is the treatment for herpes zoster?

Treatment of Herpes Zoster

For uncomplicated herpes zoster in immunocompetent adults, initiate oral valacyclovir 1000 mg three times daily for 7 days, ideally within 72 hours of rash onset, and continue treatment until all lesions have completely scabbed. 1, 2, 3

First-Line Oral Antiviral Therapy

Valacyclovir is the preferred first-line agent due to superior bioavailability, convenient dosing (three times daily versus five times daily for acyclovir), and demonstrated superiority in reducing the duration of postherpetic neuralgia compared to acyclovir. 1, 3, 4

Standard Dosing Regimens:

• Valacyclovir 1000 mg orally three times daily for 7 days (preferred) 1, 2, 3
• Famciclovir 500 mg orally three times daily for 7 days (alternative with comparable efficacy) 1, 2, 5
• Acyclovir 800 mg orally five times daily for 7-10 days (effective but less convenient dosing) 1, 2

Critical Timing Considerations:

• 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, 6
• Treatment initiated beyond 72 hours may still provide benefit, particularly for pain reduction, though effectiveness is reduced. 1, 4
• Continue treatment until all lesions have completely scabbed, not just for an arbitrary 7-day period—this is the key clinical endpoint. 1, 2

Escalation to Intravenous Therapy

Switch to intravenous acyclovir 5-10 mg/kg every 8 hours for the following indications: 1, 2

• Disseminated herpes zoster (multi-dermatomal or visceral involvement) 1, 2
• Complicated facial zoster with suspected CNS involvement 1
• Severe ophthalmic disease 1
• Immunocompromised patients with active disease 1, 2
• 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 Treatment duration should be a minimum of 7-10 days and until clinical resolution is attained. 2

Important Monitoring for IV Acyclovir:

• Monitor renal function closely at initiation and once or twice weekly during treatment, with dose adjustments for renal impairment. 1
• Assess for thrombotic thrombocytopenic purpura/hemolytic uremic syndrome in immunocompromised patients receiving high-dose therapy. 1

Special Population Considerations

Immunocompromised Patients:

• All immunocompromised patients with herpes zoster require antiviral treatment regardless of timing. 2
• Consider intravenous acyclovir for severely immunocompromised hosts (e.g., patients on chemotherapy, multiple myeloma patients). 1
• Temporary reduction in immunosuppressive medication should be considered in cases of disseminated or invasive herpes zoster. 1, 2
• Immunosuppression may be restarted after commencing anti-VZV therapy and after skin vesicles have resolved. 2
• These patients may require extended treatment duration beyond 7-10 days, as lesions develop over longer periods (7-14 days) and heal more slowly. 1, 2

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. 2

Facial/Ophthalmic Herpes Zoster:

• Requires particular urgency due to risk of ophthalmic and cranial nerve complications. 1
• Consider ophthalmology consultation for any suspected ocular involvement. 1

Acyclovir-Resistant Cases

For suspected acyclovir-resistant herpes zoster, foscarnet 40 mg/kg IV every 8 hours is the treatment of choice. 1, 2 Acyclovir-resistant isolates are routinely resistant to ganciclovir as well. 2

• Suspect resistance if lesions fail to begin resolving within 7-10 days of appropriate antiviral therapy. 1
• Obtain viral culture with susceptibility testing if resistance is suspected. 1
• Foscarnet requires close monitoring of renal function and electrolytes (hypocalcemia, hypophosphatemia, hypomagnesemia, hypokalemia). 2

Post-Exposure Prophylaxis

For varicella-susceptible patients exposed to active varicella zoster infection: 1, 2

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

Prevention: Vaccination

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

Common Pitfalls to Avoid

• Do not use topical antiviral therapy—it is substantially less effective than systemic therapy and is not recommended. 1, 2
• Do not discontinue treatment at exactly 7 days if lesions are still forming or have not completely scabbed. 1, 2
• Do not use short-course therapy designed for genital herpes (e.g., acyclovir 400 mg three times daily)—this is inadequate for VZV infection. 1
• Do not delay treatment waiting for laboratory confirmation in typical presentations—diagnosis is clinical in immunocompetent patients. 1
• Patients with active herpes zoster should avoid contact with susceptible individuals until all lesions have crusted, as lesions are contagious. 1