Shingles (Herpes Zoster) Diagnosis and Treatment
Diagnostic Criteria
Herpes zoster is primarily a clinical diagnosis based on characteristic presentation: prodromal pain preceding a unilateral vesicular eruption in a dermatomal distribution. 1
Clinical Features for Diagnosis:
- Prodromal pain that precedes skin findings by 24-72 hours, characterized by burning, itching, or paresthesia 1
- Unilateral vesicular rash confined to a single dermatome 1, 2
- Progression pattern: erythematous macules → papules → vesicles → pustules → crusting over 7-10 days 2
- Lesion evolution: new lesions continue to erupt for 4-6 days in immunocompetent hosts 1
- Total disease duration: approximately 2 weeks in otherwise healthy individuals 1
When Laboratory Confirmation is Needed:
- Atypical presentations (nonspecific lesions, faint or evanescent rash, difficult to recognize in darker skin) 1
- Immunocompromised patients with atypical clinical presentation 3
- Zoster sine herpete (pain without rash) 4
- Diagnostic methods: Tzanck smear showing giant cells, vesicle fluid for immunofluorescence antigen testing, viral culture, or PCR 1
Key Diagnostic Pitfalls:
- Do not rely solely on clinical diagnosis in immunocompromised patients or atypical presentations 3
- Consider alternative diagnoses: varicella, erysipelas, impetigo, enteroviral infections, herpes simplex 4
- Lack of rash or late-onset rash has been associated with delays in diagnosis and increased mortality 1
Treatment Recommendations
Immunocompetent Patients (Uncomplicated Disease):
Oral antiviral therapy should be initiated within 72 hours of rash onset for maximum benefit. 5, 2, 6
First-line oral antivirals (continue until all lesions have scabbed) 5:
- Acyclovir 800 mg orally 5 times daily for 7-10 days 5, 7
- Valacyclovir (better bioavailability, less frequent dosing than acyclovir) 5
- Famciclovir 500 mg three times daily for 7 days 8
Clinical efficacy data 8:
- Famciclovir 500 mg reduced median time to full crusting to 5 days vs. 7 days with placebo 8
- Effects are greater when therapy initiated within 48 hours of rash onset 8
- More profound benefit in patients ≥50 years of age 8
- Among patients who developed postherpetic neuralgia, median duration was 63 days with famciclovir vs. 119 days with placebo 8
Do NOT use topical antiviral therapy - it is substantially less effective than systemic therapy 5
Immunocompromised Patients:
High-dose intravenous acyclovir is the treatment of choice for severely immunocompromised hosts with disseminated or invasive disease. 1, 5
- IV acyclovir for disseminated or invasive herpes zoster 5
- Temporary reduction in immunosuppressive medication should be considered 5
- Oral acyclovir or valacyclovir can be used for mild cases with transient immune suppression 1
- Monitor for complications: chronic ulcerations with persistent viral replication, secondary bacterial/fungal superinfections 1
Special Populations:
Kidney transplant recipients with uncomplicated disease: oral acyclovir or valacyclovir 5
HIV-infected patients with recurrent orolabial or genital herpes: famciclovir 500 mg twice daily for 7 days is comparable to acyclovir 400 mg 5 times daily 8
Facial/ophthalmic involvement 5:
- Requires particular attention due to risk of cranial nerve complications 5
- Elevate affected area to promote drainage 5
- Keep skin well hydrated with emollients 5
- Trigeminal or ophthalmic involvement causes more severe pain 1
Adjunctive Therapies
Corticosteroids:
Prednisone may be used as adjunctive therapy to antivirals in select cases of severe, widespread disease, but carries significant risks in elderly patients. 5
- Avoid in immunocompromised patients due to increased risk of disseminated infection 5
- Modest benefits in reducing pain and incidence of postherpetic neuralgia when combined with antivirals 6
Pain Management:
- Acute pain: analgesics, NSAIDs 9
- Postherpetic neuralgia (pain persisting ≥90 days): topical lidocaine or capsaicin, oral gabapentin, pregabalin, or tricyclic antidepressants 2, 6
Prevention
The recombinant zoster vaccine (Shingrix) is recommended for adults aged 50 years and older, regardless of prior episodes of herpes zoster. 5, 10
- CDC recommends vaccination for adults ≥60 years 2
- Offers robust protection against herpes zoster and complications 10
- Can be considered after recovery to prevent future episodes 5
Post-Exposure Prophylaxis:
Varicella zoster immunoglobulin (or IVIG) within 96 hours of exposure for varicella-susceptible patients exposed to active infection 5
If immunoglobulin unavailable or >96 hours have passed: 7-day course of oral acyclovir beginning 7-10 days after exposure 5
Key Clinical Pearls
- Antiviral medications do not eradicate latent virus but control symptoms and reduce complications 5
- Viral shedding peaks in first 24 hours after lesion onset when most lesions are vesicular 3
- Immunocompromised patients are at 20-100 times higher risk of developing herpes zoster 2
- Monitor for complete healing of all lesions 5
- Patients may be contagious to susceptible individuals due to virus particles in vesicle fluid 4