What is the recommended treatment and prescription for herpes zoster?

Treatment of Herpes Zoster

For uncomplicated herpes zoster, prescribe valacyclovir 1 gram orally three times daily for 7 days, initiated within 72 hours of rash onset. 1

First-Line Oral Antiviral Options

Valacyclovir is the preferred first-line agent due to its convenient dosing schedule and proven efficacy in reducing acute pain duration and preventing postherpetic neuralgia. 1, 2

Alternative oral regimens include:

• Acyclovir 800 mg orally five times daily for 7 days 1, 2
• Famciclovir 500 mg orally three times daily for 7 days 1, 3

The twice-daily valacyclovir regimen (1.5 g twice daily) has been studied and shows comparable efficacy to three-times-daily dosing, though the standard recommendation remains 1 gram three times daily. 4

Critical Timing Considerations

Antiviral therapy must be initiated within 72 hours of rash onset for optimal effectiveness, though treatment within 48 hours provides the greatest benefit. 1, 5, 3 Delayed initiation beyond 72 hours significantly reduces treatment effectiveness. 1

Continue treatment until all lesions have completely scabbed, not just for an arbitrary 7-day period—this is the key clinical endpoint. 1, 2 In immunocompromised patients, lesions may continue to develop for 7-14 days and heal more slowly, requiring treatment extension well beyond the standard 7-10 days. 2

Indications for Intravenous Therapy

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

• Disseminated or multi-dermatomal herpes zoster 1, 2
• Visceral involvement or CNS complications 1, 2
• Ophthalmic zoster with severe complications 1
• Immunocompromised patients with severe disease 1, 2
• Patients unable to tolerate oral therapy 1

Continue IV therapy until clinical improvement occurs, then switch to oral therapy to complete the treatment course. 1 Treatment should continue for a minimum of 7-10 days and until clinical resolution is attained. 1

Special Population Considerations

Immunocompromised Patients

All immunocompromised patients with herpes zoster require antiviral treatment regardless of timing. 1 Consider temporary reduction or discontinuation of immunosuppressive medications in cases of disseminated or invasive disease. 1, 2 Monitor closely for dissemination and visceral complications. 1

Patients Over 50 Years

Systemic antiviral therapy is urgently indicated in all patients beyond age 50, as this population faces significantly increased risk of postherpetic neuralgia and severe complications. 5

Facial/Ophthalmic Involvement

Herpes zoster in the head and neck area, especially zoster ophthalmicus, requires urgent antiviral therapy due to risk of vision-threatening complications and cranial nerve involvement. 1, 5 Consider ophthalmology referral for ocular involvement. 6

Acyclovir-Resistant Cases

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

Renal Dosing Adjustments

Dose adjustments are mandatory in patients with renal impairment to prevent acute renal failure. 1, 2 For famciclovir in herpes zoster with creatinine clearance 20-39 mL/min, reduce to 500 mg every 24 hours. 1 Monitor renal function closely during IV acyclovir therapy. 2

Common Pitfalls to Avoid

• Do not use topical antiviral therapy—it is substantially less effective than systemic therapy and is not recommended. 2
• Do not rely on the 400 mg three-times-daily acyclovir dose—this is only appropriate for genital herpes or HSV suppression, not for shingles. 2
• Do not stop treatment at 7 days if lesions remain active—continue until all lesions have scabbed. 1, 2
• Do not delay treatment waiting for laboratory confirmation in typical presentations—diagnosis is primarily clinical. 5

Post-Exposure Prophylaxis

For varicella-susceptible patients exposed to active varicella zoster infection, administer varicella zoster immunoglobulin within 96 hours of exposure. 1, 2 If immunoglobulin is unavailable or more than 96 hours have passed, prescribe a 7-day course of oral acyclovir beginning 7-10 days after exposure. 1, 2

Vaccination for Prevention

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. 2 The vaccine can be considered after recovery to prevent future episodes. 2