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derm.herpes-zoster.core.v1PRODUCTION
derm.herpes-zoster.core.v1

Herpes zoster (shingles) — acute reactivation, complications & PHN

dermatologyacuteadultgeriatric
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12/12 authored

Canonical 12-phase frame with authored status for this dossier.

Current phase

Frame

Detailed

Acute zoster reactivation, skin-first: confirm dermatomal vesicular rash, decide antiviral timing, screen complications, and pre-set the PHN-prevention + RZV-handoff arc (Cohen NEJM 2013; Dworkin CID 2007). Disseminated/visceral routes to id.sepsis.core.v1 / immunocompromised pathway; ocular to ophtho.*; oticus to neuro.bell-palsy.v1

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scope confirmed; lifespan-VZV/vaccine overlap delegated to id.varicella-zoster.v1

Patient inputs (14)

HIV/transplant/chemo/high-dose steroid/biologic → disseminated & visceral risk; lower threshold for IV acyclovir + admission (Cohen NEJM 2013; Dworkin CID 2007)

Age ≥50 (esp. ≥60) is the dominant PHN risk factor and RZV-eligibility driver (Lal NEJM 2015; Dooling MMWR 2018)

Baseline 0–10 pain score anchors acute analgesia ladder and PHN trajectory monitoring (Dworkin CID 2007)

Single-dermatome vs multidermatomal/disseminated drives immunocompromise workup and IV-vs-PO decision (Cohen NEJM 2013; Dworkin CID 2007)

Antiviral benefit is greatest within 72 h of rash onset; ongoing new-vesicle formation extends the treatment window (Dworkin CID 2007 — T_treat anchor)

Trigeminal V1 / nasociliary (Hutchinson) involvement = ocular-threatening → emergent ophthalmology (Liesegang Ophthalmology 2008; AAO HZO PPP)

Keratitis/uveitis/acute retinal necrosis risk in HZO — vision-threatening (AAO HZO PPP; Liesegang 2008)

Ramsay Hunt: peripheral CN VII palsy + ear vesicles; worse recovery than Bell palsy without prompt antiviral+steroid (Sweeney JNNP 2001)

Headache, confusion, focal deficit, meningismus → VZV encephalitis/meningitis/vasculopathy → LP + IV acyclovir (Gershon 2015)

Acyclovir/valacyclovir/famciclovir + gabapentinoid renal dose adjustment; IV acyclovir crystal nephropathy risk (Dworkin CID 2007)

Zoster in a younger adult or multidermatomal disease is an HIV-indicator condition — offer HIV testing (CDC)

Acyclovir/valacyclovir preferred antivirals in pregnancy; avoid gabapentinoid/TCA first-line; RZV deferred (CDC; ACOG)

Pain persisting ≥90 days after rash onset defines PHN and triggers the neuropathic ladder (Dworkin CID 2007)

Lesion-swab VZV PCR confirms atypical/disseminated/immunocompromised or HZO/Ramsay Hunt cases (Cohen NEJM 2013 — highest-yield test)

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (8)

8 need judgement
  • informationallife_threateningdisseminated_zoster
    >2 non-contiguous dermatomes OR generalized vesicles beyond primary dermatome (>20 lesions outside) — disseminated VZV (Cohen NEJM 2013)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningvisceral_or_cns_vzv
    Pneumonitis, hepatitis, encephalitis/meningitis, myelitis, or VZV vasculopathy (headache, confusion, focal deficit, stroke) (Gershon 2015)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverezoster_ophthalmicus_with_ocular_signs
    V1 dermatome ± Hutchinson sign (nasociliary/nasal-tip vesicle) WITH ocular pain, redness, photophobia, or vision change (Liesegang Ophthalmology 2008; AAO HZO PPP)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereramsay_hunt_syndrome
    Auricular/canal/oral vesicles + ipsilateral peripheral facial palsy ± vertigo/hearing loss (zoster oticus) (Sweeney JNNP 2001)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverezoster_in_immunocompromised_host
    Zoster in HIV/transplant/chemotherapy/high-dose-steroid/biologic host (Cohen NEJM 2013; Dworkin CID 2007)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseveresacral_zoster_with_retention
    S2–S4 sacral zoster with urinary retention or bowel/bladder dysfunction (zoster-associated neurogenic bladder) (Cohen NEJM 2013)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateantiviral_window_open
    Rash onset <72 h OR new vesicles still forming (active viral replication) (Dworkin CID 2007)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatesevere_acute_zoster_pain_phn_risk
    Severe acute pain (NRS ≥7) and/or age ≥60 and/or ophthalmic site — high PHN risk (Dworkin CID 2007)
    Trigger could not be auto-evaluated — needs clinician judgement.

Workflow calculators

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Recommended regimen

Zoster antiviral by host & complication site
axis: zoster_antiviral_by_host_and_site
Selected axis "Zoster antiviral by host & complication site" by default fallback (first axis)
  • valacyclovir
    first line
    guanosine_analogue_prodrug
    1 g • PO • TID (max: 3 g/day)
    triggers: immunocompetent_localized, within_72h_or_new_vesicles
    Dworkin CID 2007 / Beutner AAC 1995 — preferred PO antiviral; higher bioavailability than acyclovir, faster zoster-associated pain resolution; ×7 days (10–14 d for HZO)
    rxcui 73645
  • famciclovir
    first line
    guanosine_analogue_prodrug
    500 mg • PO • TID (max: 1500 mg/day)
    triggers: immunocompetent_localized, valacyclovir_unavailable
    Tyring Arch Fam Med 2000 — equivalent efficacy to acyclovir, TID dosing; ×7 days
    rxcui 68099
  • acyclovir
    first line
    guanosine_analogue
    800 mg • PO • 5×/day (max: 4000 mg/day)
    triggers: pregnancy, cost_constrained, within_72h_or_new_vesicles
    Dworkin CID 2007 — effective; preferred antiviral in pregnancy (most safety data); inconvenient 5×/day dosing; ×7–10 days
    rxcui 281
  • acyclovir (IV)
    rescue
    guanosine_analogue
    10 mg/kg • IV • q8h (max: per renal function)
    triggers: disseminated, visceral, cns_involvement, severe_immunocompromise, sight_threatening_hzo
    Gershon 2015 / Dworkin CID 2007 — IV acyclovir 10 mg/kg q8h ×7–10 d for disseminated/visceral/CNS/sight-threatening or severely immunocompromised; ensure hydration to prevent crystal nephropathy
    rxcui 281
  • prednisone
    add on
    corticosteroid
    60 mg taper • PO • once daily taper over 2–3 wk (max: 60 mg/day)
    triggers: ramsay_hunt, severe_acute_pain_immunocompetent, no_steroid_contraindication
    Wood NEJM 1994 — adjunctive prednisone improves acute pain/QoL in selected immunocompetent adults and is used in Ramsay Hunt with antiviral; does NOT reduce PHN incidence; avoid in immunocompromise/uncontrolled DM/contraindications
    rxcui 8640

outpatient playbook — drug actions (4)

  1. 1. valacyclovir
    rxcui 73645
    1 g PO • PO • TID ×7 d
    trigger: Immunocompetent localized within 72 h or new vesicles (Dworkin CID 2007)
    Beutner AAC 1995 — preferred PO antiviral; faster pain resolution
  2. 2. famciclovir (alternative)
    rxcui 68099
    500 mg PO • PO • TID ×7 d
    trigger: Valacyclovir unavailable (Tyring 2000)
    Tyring 2000 — equivalent, TID
  3. 3. acyclovir (pregnancy/cost)
    rxcui 281
    800 mg PO • PO • 5×/day ×7–10 d
    trigger: Pregnancy or cost-constrained (Dworkin CID 2007)
    Dworkin CID 2007 — most pregnancy safety data
  4. 4. acute analgesia
    acetaminophen ± short opioid; add gabapentin if severe • PO • scheduled + PRN
    trigger: Baseline pain NRS ≥4 (Dworkin CID 2007)
    Dworkin CID 2007 — early analgesia; gabapentinoid for severe acute neuritic pain

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Unilateral grouped vesicles on erythematous base in a single dermatome, not crossing midline (Cohen NEJM 2013 — pathognomonic; Dworkin CID 2007); Burning/lancinating dermatomal pain or dysaesthesia preceding rash by 1–5 days (Cohen NEJM 2013 — preherpetic neuralgia); V1 (ophthalmic) rash, eyelid involvement, or vesicle on nasal tip/side (Hutchinson sign) (Liesegang Ophthalmology 2008 — HZO emergency).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Herpes zoster (shingles) — acute reactivation, complications & PHN** (derm.herpes-zoster.core.v1).
Phenotype framing: Zosteriform HSV (recurrent, smaller cluster, PCR-typed), contact/allergic dermatitis (pruritic, exposure-patterned, non-dermatomal), early cellulitis/erysipelas (no vesicles, warmth, systemic), bullous impetigo, insect bites, dermatomal pain mimics (MI/biliary/renal colic before rash) (Cohen NEJM 2013)
Scope: Acute zoster reactivation, skin-first: confirm dermatomal vesicular rash, decide antiviral timing, screen complications, and pre-set the PHN-prevention + RZV-handoff arc (Cohen NEJM 2013; Dworkin CID 2007). Disseminated/visceral routes to id.sepsis.core.v1 / immunocompromised pathway; ocular to ophtho.*; oticus to neuro.bell-palsy.v1

No severity triggers fired against current inputs.

Plan

Regimen axis: **Zoster antiviral by host & complication site**.
1. valacyclovir 1 g PO TID (guanosine_analogue_prodrug, first line) — Dworkin CID 2007 / Beutner AAC 1995 — preferred PO antiviral; higher bioavailability than acyclovir, faster zoster-associated pain resolution; ×7 days (10–14 d for HZO)
2. famciclovir 500 mg PO TID (guanosine_analogue_prodrug, first line) — Tyring Arch Fam Med 2000 — equivalent efficacy to acyclovir, TID dosing; ×7 days
3. acyclovir 800 mg PO 5×/day (guanosine_analogue, first line) — Dworkin CID 2007 — effective; preferred antiviral in pregnancy (most safety data); inconvenient 5×/day dosing; ×7–10 days
4. acyclovir (IV) 10 mg/kg IV q8h (guanosine_analogue, rescue) — Gershon 2015 / Dworkin CID 2007 — IV acyclovir 10 mg/kg q8h ×7–10 d for disseminated/visceral/CNS/sight-threatening or severely immunocompromised; ensure hydration to prevent crystal nephropathy
5. prednisone 60 mg taper PO once daily taper over 2–3 wk (corticosteroid, add on) — Wood NEJM 1994 — adjunctive prednisone improves acute pain/QoL in selected immunocompetent adults and is used in Ramsay Hunt with antiviral; does NOT reduce PHN incidence; avoid in immunocompromise/uncontrolled DM/contraindications

Setting playbook (outpatient) — Immunocompetent localized non-ophthalmic zoster: start PO antiviral within 72 h, control acute pain, screen ophthalmic/oticus complications, set PHN surveillance + RZV handoff (Dworkin CID 2007; Cohen NEJM 2013)
6. valacyclovir 1 g PO PO TID ×7 d — Immunocompetent localized within 72 h or new vesicles (Dworkin CID 2007) (Beutner AAC 1995 — preferred PO antiviral; faster pain resolution)
7. famciclovir (alternative) 500 mg PO PO TID ×7 d — Valacyclovir unavailable (Tyring 2000) (Tyring 2000 — equivalent, TID)
8. acyclovir (pregnancy/cost) 800 mg PO PO 5×/day ×7–10 d — Pregnancy or cost-constrained (Dworkin CID 2007) (Dworkin CID 2007 — most pregnancy safety data)
9. acute analgesia acetaminophen ± short opioid; add gabapentin if severe PO scheduled + PRN — Baseline pain NRS ≥4 (Dworkin CID 2007) (Dworkin CID 2007 — early analgesia; gabapentinoid for severe acute neuritic pain)

Non-pharmacologic actions:
- Keep lesions covered until crusted; hygiene to limit varicella transmission to susceptibles (CDC)
- Counsel return precautions for eye/ear/CNS symptoms (Liesegang 2008; Sweeney 2001)
- Schedule PHN review and RZV at ≥50 once resolved (Dooling MMWR 2018)

AVOID / contraindication checks:
- Acyclovir renal dose and hydration (Dworkin CID 2007 — adjust for eGFR; IV crystal nephropathy)
- Valacyclovir TTP HUS in severe immunocompromise (high dose valacyclovir caution in advanced HIV/transplant)
- Prednisone avoid if immunocompromised or contraindicated (Wood NEJM 1994 — not for PHN prevention)

Monitoring

Regimen monitoring:
- rash crusting 7-10d (Cohen NEJM 2013)
- renal function during antiviral (Dworkin CID 2007)
- pain NRS trajectory to 90d (Dworkin CID 2007 — PHN surveillance)

Setting (outpatient) monitoring:
- Rash crusting at 7–10 d; pain NRS at 1–2 wk and ~90 d (Dworkin CID 2007)
- Renal tolerance of antiviral (Dworkin CID 2007)

Follow-up plan: PHN screen at ≥90 d (gabapentin/pregabalin → TCA (nortriptyline) → lidocaine 5% patch → capsaicin/opioid escalation); secondary prevention: 2-dose RZV (Shingrix) ≥50 routine and ≥19 immunocompromised — administer after acute episode resolves (Dworkin CID 2007; Rice Pain 2001; Dworkin Pain 2003; Dooling MMWR 2018; Anderson MMWR 2022)
- Close-out criterion: PHN plan + RZV handoff documented

Monitoring phase: Reassess rash crusting (~7–10 d), pain trajectory, antiviral tolerance/renal function; HZO → serial ophthalmology; Ramsay Hunt → House-Brackmann grading + audiometry; watch for dissemination if immunocompromised (Dworkin CID 2007; AAO HZO PPP)

Disposition

Current setting: outpatient — Immunocompetent localized non-ophthalmic zoster: start PO antiviral within 72 h, control acute pain, screen ophthalmic/oticus complications, set PHN surveillance + RZV handoff (Dworkin CID 2007; Cohen NEJM 2013)

Disposition criteria:
- Continue outpatient if immunocompetent, localized, oral-tolerant, reliable (Cohen NEJM 2013)
- Escalate to ED/admit if complication red flag or cannot take PO (Gershon 2015)

Escalation triggers (move to higher acuity):
- Any V1/Hutchinson + ocular symptom → emergent ophthalmology (Liesegang 2008)
- Facial palsy + ear vesicles → Ramsay Hunt pathway, urgent ENT/neuro (Sweeney 2001)
- >2 non-contiguous dermatomes / visceral / CNS → ED + IV acyclovir (Gershon 2015)
- Severe immunocompromise → low admission threshold (Cohen NEJM 2013)

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] >2 non-contiguous dermatomes OR generalized vesicles beyond primary dermatome (>20 lesions outside) — disseminated VZV (Cohen NEJM 2013)
- [LIFE_THREATENING] Pneumonitis, hepatitis, encephalitis/meningitis, myelitis, or VZV vasculopathy (headache, confusion, focal deficit, stroke) (Gershon 2015)
- [SEVERE] V1 dermatome ± Hutchinson sign (nasociliary/nasal-tip vesicle) WITH ocular pain, redness, photophobia, or vision change (Liesegang Ophthalmology 2008; AAO HZO PPP)

Citations

- IDSA HSV-VZV management (Dworkin CID 2007) + Cohen NEJM 2013 clinical practice review + Gershon Nat Rev Dis Primers 2015 + ACIP RZV recommendations (Dooling MMWR 2018; Anderson MMWR 2022) + AAO Herpes Zoster Ophthalmicus PPP + CDC Shingles clinical guidance (current 2026 floor) [PMID:17143845](https://pubmed.ncbi.nlm.nih.gov/17143845/)
- Cited evidence (PMID 23863052) [PMID:23863052](https://pubmed.ncbi.nlm.nih.gov/23863052/)
- Cited evidence (PMID 27188665) [PMID:27188665](https://pubmed.ncbi.nlm.nih.gov/27188665/)
- Cited evidence (PMID 25916341) [PMID:25916341](https://pubmed.ncbi.nlm.nih.gov/25916341/)
- Cited evidence (PMID 27626517) [PMID:27626517](https://pubmed.ncbi.nlm.nih.gov/27626517/)

Last reconciled with current guidelines: 2026-05-22.
References
  • IDSA HSV-VZV management (Dworkin CID 2007) + Cohen NEJM 2013 clinical practice review + Gershon Nat Rev Dis Primers 2015 + ACIP RZV recommendations (Dooling MMWR 2018; Anderson MMWR 2022) + AAO Herpes Zoster Ophthalmicus PPP + CDC Shingles clinical guidance (current 2026 floor) — PMID:17143845
  • Cited evidence (PMID 23863052) — PMID:23863052
  • Cited evidence (PMID 27188665) — PMID:27188665
  • Cited evidence (PMID 25916341) — PMID:25916341
  • Cited evidence (PMID 27626517) — PMID:27626517