Acyclovir in Herpes Zoster (Shingles): Complete Practical Guide
- Mayta
- 1 hour ago
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1. Acyclovir in Herpes zoster (Shingles)
Standard oral regimen
Acyclovir
Dose: 800 mg
Frequency: 5×/day (approximately q4h while awake)
Route: oral (po)
Duration: 7 days
When to start
Best: within 72 hours of rash onset
Still start after 72 hours if:
New vesicles are still appearing
Severe pain
Elderly (>50 years)
Immunocompromised
Ophthalmic zoster
2. What if NOT improved? (very important)
🔎 First: define “not improved”
This determines everything.
NOT improved = still ACTIVE
New vesicles are still appearing
Fluid-filled blisters remain
Rash still evolving
✅ Improved (even if pain remains)
No new vesicles ≥48 hours
Lesions drying / crusting
Only pain remains → nerve inflammation, not virus
Stepwise management with acyclovir
▶️ Step 1: After 7 days of acyclovir
If lesions still active / new vesicles present
✅ Extend acyclovir to TOTAL 10 days
Same dose: 800 mg
Same frequency: 5×/day
➜ Add +3 days
📌 Do NOT restart a new course
📌 Do NOT increase the dose
▶️ Step 2: After 10 days of oral acyclovir
🟢 Case A: Lesions crusted, no new vesicles
➡️ STOP acyclovir
➡️ Treat pain (PHN / subacute neuralgia)
❌ Continuing acyclovir gives no benefit
🔴 Case B: Still NEW vesicles after 10 days (rare, serious)
➡️ Treatment failure → reassess
Think of:
Immunocompromised state
Poor compliance
Severe / disseminated zoster
Acyclovir resistance (rare)
Management
✅ Admit (IPD) ✅ Switch to IV acyclovir
10 mg/kg IV q8h
7–10 days
Adjust for renal function
📌 This is NOT OPD anymore
❌ What you should NEVER do
❌ Extend oral acyclovir beyond 10 days routinely
❌ Increase oral dose above 800 mg
❌ Continue antivirals just because pain persists
❌ Add topical acyclovir for shingles
3. Acyclovir CREAM — when to use?
❌ In Herpes zoster (shingles)
NOT recommended
Why?
Zoster = deep nerve (ganglion) infection
Topical acyclovir:
Poor penetration
Does NOT reduce pain
Does NOT shorten disease
Does NOT prevent PHN
Shingles → systemic antivirals ONLY
🟡 What about Chickenpox (Varicella)?
Acyclovir oral — YES (in selected patients)
Adults
Adolescents
Severe disease
Immunocompromised
Oral acyclovir can reduce severity if started early.
Acyclovir cream in chickenpox?
❌ Still NOT recommended routinely
Why?
Chickenpox has systemic viremia
Topical cream does NOT change disease course
What is used topically in chickenpox?
✅ Symptomatic care only
Calamine lotion
Antihistamines (itching)
Keep nails short / skin clean
📌 Some mild HSV lesions use topical acyclovir — NOT varicella or zoster
High-yield summary
Herpes zoster:Acyclovir 800 mg po 5×/day × 7 days If still active → extend to 10 days total If still active after 10 days → IV acyclovir Acyclovir cream: ❌ No role in shingles ❌ No routine role in chickenpox ✅ Mainly for HSV only
Management of Herpes zoster (Shingles): a complete, practical guide (OPD + when to admit)
Herpes zoster = reactivation of varicella-zoster virus (VZV) in a sensory ganglion → unilateral, dermatomal pain + vesicular rash. (CDC)
1) Goals of treatment
✅ Shorten rash duration & viral shedding✅ Reduce acute pain and improve function✅ Prevent / detect early complications (eye, ear, CNS, dissemination) (CDC)
Pearl: Antivirals help the acute episode, but do not reliably prevent PHN. (AAFP)
2) Diagnosis & severity check (first 2 minutes)
Typical diagnosis (clinical)
Dermatomal, unilateral vesicles on erythematous base + neuropathic pain. (AAFP)
When you might test (PCR)
Atypical rash, recurrent/unclear vs HSV, disseminated disease, immunocompromised. (AAFP)
“Red flags” = urgent referral / ED
Eye involvement: rash on forehead/eyelid, red eye, vision change, photophobia
Ear involvement / facial weakness (Ramsay Hunt pattern)
Disseminated zoster (widespread lesions), severe systemic symptoms
Neurologic signs: headache, neck stiffness, confusion, weakness
Immunocompromised (HIV, chemo, transplant, high-dose steroids, etc.) (CDC)
3) Setting: OPD vs IPD
OPD (most uncomplicated cases)
Localized rash, stable vitals, can take oral meds, no eye/ear/CNS signs.
IPD / ED (admit or urgent specialist)
Severe disease or immunocompromised with severe/disseminated disease
Ophthalmic/otic complications, CNS complications, unable to hydrate orally, uncontrolled pain. (AAFP)
4) Definitive treatment: Antivirals (core of management)
When to start
✅ Best: within 72 hours of rash onset
✅ Still treat even >72h if new vesicles are still appearing OR complications (eye/neurologic). (AAFP)
Standard oral regimens (adult)
(Choose one, based on availability/renal function)
Valacyclovir 1 g po q8h × 7 days Famciclovir 500 mg po q8h × 7 days (often 10 days if immunocompromised) Acyclovir 800 mg po 5×/day (during waking hours) × 7 days
Practical: valacyclovir/famciclovir are easier adherence than acyclovir (5×/day). (AAFP)
How to judge response (this answers your earlier question)
ACTIVE = any new vesicles / fluid-filled blisters still forming IMPROVING = no new vesicles for ~48h + lesions drying/crusting (pain may persist). (AAFP)
If lesions still active at day 7
✅ Extend to 10 days total (i.e., +3 days) at the same dose
Especially if immunocompromised or new lesions continue.
If still “not improved” after 10 days
5) IPD/severe disease: IV antiviral (when indicated)
✅ IV acyclovir is commonly used for severe/disseminated disease, especially in immunocompromised individuals. (AAFP)
Typical dosing referenced in product labeling: 10 mg/kg IV q8h (renal adjust). (FDA Access Data)
6) Supportive treatment (pain + skin care)
Pain ladder (exam + real life)
Mild–moderate pain: Paracetamol ± NSAID (if no contraindication).
Neuropathic pain (burning/shooting/allodynia): gabapentin/pregabalin or TCA (e.g., amitriptyline/nortriptyline). (AAFP)
Severe pain: short course opioid may be needed (with caution), plus neuropathic agent.
Skin care
Keep clean/dry, non-adherent dressings if needed.
Treat secondary bacterial infection if signs of impetiginization/cellulitis. (CDC)
7) Steroids: when to use (and when NOT)
✅ Steroids can reduce acute pain and speed early healing ONLY as an adjunct with antivirals in selected patients. (AAFP)
❌ Do NOT use steroids alone (risk without antiviral cover; no PHN prevention). (AAFP)
8) Acyclovir cream — when to use?
❌ Not recommended for shingles (zoster is a nerve/ganglion infection; major guidance focuses on systemic antivirals). Inference based on standard recommendations listing oral/IV antivirals rather than topical therapy.
✅ Acyclovir cream is mainly for HSV (cold sores/genital herpes), not zoster.
9) Post-herpetic neuralgia (PHN): prevention & treatment
Definition: pain persisting ≥90 days after acute zoster rash. (AAFP)Treatment options (symptom control):
Topical lidocaine/capsaicin
Gabapentin/pregabalin
TCA (amitriptyline/nortriptyline/desipramine) (AAFP)
10) Infection control & counseling (must tell patients)
Cover rash, avoid touching/scratching, hand hygiene
Contagious until rash has scabbed over
Avoid contact (until scabbed): pregnant non-immune, premature infants, immunocompromised (CDC)
11) Vaccination (prevention)
CDC recommends 2 doses of recombinant zoster vaccine (Shingrix):
Age ≥50 (immunocompetent)
Age ≥19 if immunodeficient/immunosuppressed (CDC)(Usually 2–6 months apart; vaccinate after the acute episode resolves.)
12) Follow-up (simple, practical)
✅ Recheck 48–72 hours after starting antivirals (earlier if high risk) to confirm:
No new vesicles
Pain controlled
No eye/ear/neuro red flags Then follow up at 1–2 weeks for healing and PHN screening.
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