What is the recommended treatment for shingles (herpes zoster) in an adult?

Treatment of Shingles (Herpes Zoster)

Initiate oral valacyclovir 1000 mg three times daily for 7-10 days immediately, ideally within 72 hours of rash onset, and continue treatment until all lesions have completely scabbed. 1, 2, 3

First-Line Antiviral Therapy

Valacyclovir is the preferred first-line agent due to superior bioavailability and less frequent dosing (three times daily vs. five times daily), which improves adherence compared to acyclovir. 1, 4

Standard Oral Regimens for Immunocompetent Adults:

• Valacyclovir 1000 mg three times daily for 7-10 days 1, 3, 4
• Acyclovir 800 mg five times daily for 7-10 days (effective alternative if valacyclovir unavailable) 1, 2, 3
• Famciclovir 500 mg three times daily for 7-10 days (comparable efficacy with convenient dosing) 1, 5, 4

Critical Treatment Endpoint:

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 Treatment may need to extend beyond 7-10 days in immunocompromised patients, as their lesions develop over longer periods (7-14 days) and heal more slowly. 2

Timing Window:

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, 3, 6 However, observational data suggest valacyclovir may still provide benefit when started beyond 72 hours, so do not withhold treatment in late-presenting patients. 4

When to Escalate to Intravenous Therapy

Switch to intravenous acyclovir 10 mg/kg every 8 hours if any of the following occur: 1, 2, 7

• Disseminated herpes zoster (≥3 dermatomes, visceral involvement, or hemorrhagic lesions)
• Suspected CNS involvement (encephalitis, meningitis)
• Complicated ocular or facial disease (including Ramsay Hunt syndrome with facial paralysis)
• Severe immunocompromise (active chemotherapy, HIV with low CD4 count, organ transplant)
• Inability to take oral medications
• Failure to respond to oral therapy within 7-10 days

Continue IV acyclovir for a minimum of 7-10 days and until clinical resolution (all lesions completely scabbed). 2

Special Populations

Immunocompromised Patients:

• Uncomplicated herpes zoster: Oral valacyclovir or acyclovir with close outpatient follow-up 2, 7
• Disseminated or invasive disease: IV acyclovir 10 mg/kg every 8 hours with temporary reduction in immunosuppressive medications when clinically feasible 2
• Monitor closely for signs of cutaneous and visceral dissemination; if signs occur, escalate to IV therapy immediately 8, 7

Renal Impairment:

Monitor renal function at initiation and once or twice weekly during treatment, particularly in elderly patients or those with baseline renal impairment, as dose adjustments are mandatory to prevent acute renal failure. 1, 2

Acyclovir-Resistant Herpes Zoster

If lesions fail to begin resolving within 7-10 days despite appropriate therapy, suspect acyclovir resistance (occurs in up to 7% of immunocompromised patients but is extremely rare in immunocompetent patients). 2 Obtain viral culture with susceptibility testing and switch to foscarnet 40 mg/kg IV every 8 hours until clinical resolution. 1, 2 All acyclovir-resistant strains are also resistant to valacyclovir, and most are resistant to famciclovir. 2

Adjunctive Pain Management

• Over-the-counter analgesics (acetaminophen, ibuprofen) for acute pain relief 2
• Topical ice or cold packs to reduce pain and swelling during the acute phase 2
• Avoid topical antivirals—they are substantially less effective than systemic therapy and are not recommended 2
• Oral corticosteroids may provide modest benefits in reducing acute pain but carry significant risks (infections, hypertension, myopathy, glaucoma, osteopenia) and should be avoided in immunocompromised patients due to increased risk of disseminated infection 1, 2

Infection Control

Patients should avoid contact with susceptible individuals (pregnant women who are varicella-seronegative, immunocompromised persons, infants) until all lesions have crusted, as the virus can be transmitted and cause varicella in susceptible contacts. 1, 2 Cover lesions with clothing or dressings to minimize transmission risk. 2

Prevention of Future Episodes

The recombinant zoster vaccine (Shingrix) is strongly recommended for all adults aged ≥50 years, regardless of prior herpes zoster episodes, providing >90% efficacy in preventing future recurrences. 1, 2, 9 Administer the 2-dose series (second dose 2-6 months after the first) once acute symptoms have resolved, typically waiting at least 2 months after the episode. 9 Having one episode of shingles does not provide reliable protection against future recurrences (10.3% cumulative recurrence risk at 10 years). 9

Common Pitfalls to Avoid

• Do not use short-course therapy designed for genital herpes (e.g., acyclovir 400 mg three times daily)—this is inadequate for VZV infection 2
• Do not apply topical corticosteroids to active shingles lesions—this can increase risk of severe disease and dissemination, particularly in immunocompromised patients 2
• Do not delay treatment waiting for laboratory confirmation—clinical diagnosis is sufficient in immunocompetent patients with typical presentation 2
• Do not stop antivirals at exactly 7 days if lesions remain active—continue until complete scabbing 1, 2