Dermatology · PANCE / PANRE

Herpes Zoster (Shingles)

Written & clinically reviewed by Ryan Busch, PA-C · Updated August 2026 · Report an error

Reactivation of latent VZV in a dorsal root ganglion → painful unilateral dermatomal vesicular eruption.

Also known as: herpes zoster, shingles, zoster, postherpetic neuralgia, zoster ophthalmicus

Overview

Reactivation of varicella-zoster virus (VZV) latent in dorsal root or cranial nerve ganglia, producing a painful unilateral vesicular eruption confined to one or two adjacent dermatomes.

Epidemiology

Lifetime risk ~30% in the US; incidence rises sharply after age 50. ~1 million US cases annually. Increased severity, duration, and risk of postherpetic neuralgia (PHN) with age and immunosuppression.

Try two board-style Herpes Zoster questions

Real questions from the FirstPassPA bank, with the full explanation. Pick an answer — no signup, no email.

Question 1DermatologyMedium
A 72-year-old has a painful dermatomal vesicular rash on the right chest. Which of the following complications is most likely?
  • AHerpes zoster ophthalmicus with keratitis
  • BRamsay Hunt facial nerve palsy
  • CDisseminated zoster across multiple dermatomes
  • DPostherpetic neuralgia in the dermatome
Reveal answer & full explanation
Correct answer: D — Postherpetic neuralgia in the dermatome
  • AHerpes zoster ophthalmicus with keratitis
  • BRamsay Hunt facial nerve palsy
  • CDisseminated zoster across multiple dermatomes
  • DPostherpetic neuralgia in the dermatome✓

Why Postherpetic neuralgia in the dermatome is correct

  • Herpes zoster results from varicella-zoster reactivation in a sensory ganglion, here the thoracic dermatome.
  • Postherpetic neuralgia in the dermatome is the most common complication overall and its risk rises sharply with older age, as in this 72-year-old.
  • Early antiviral therapy reduces acute pain and the likelihood of persistent neuralgia.

Why the others are wrong

  • Disseminated zoster across multiple dermatomes — Dissemination mainly occurs in immunocompromised hosts and is far less common than postherpetic neuralgia in an otherwise healthy older adult.
  • Ramsay Hunt facial nerve palsy — Ramsay Hunt follows geniculate-ganglion zoster with ear vesicles and facial palsy, not a thoracic dermatomal rash.
  • Herpes zoster ophthalmicus with keratitis — Ophthalmic zoster arises from V1 trigeminal involvement, not the chest dermatome described here.
Question 2DermatologyEasy
A 64-year-old woman presents with a painful rash on her right flank. For 3 days before the rash she felt a burning, tingling pain in a band across that area. On exam there are grouped vesicles on an erythematous base distributed in a single band wrapping from her mid-back to the right side of her abdomen; the eruption stops sharply at the midline and does not cross to the left side. She reports the area is exquisitely tender to light touch. Which of the following is the most likely diagnosis?
  • AAllergic contact dermatitis
  • BHerpes zoster
  • CZosteriform herpes simplex
  • DBullous pemphigoid
Reveal answer & full explanation
Correct answer: B — Herpes zoster
  • AAllergic contact dermatitis
  • BHerpes zoster✓
  • CZosteriform herpes simplex
  • DBullous pemphigoid

Why Herpes zoster is correct

  • Reactivation of latent varicella-zoster virus produces the classic picture seen here: a prodrome of dermatomal burning/tingling pain 1-5 days before the rash, followed by grouped vesicles on an erythematous base.
  • The hallmark is a unilateral eruption confined to one or two adjacent dermatomes that respects the midline and does not cross it; the thoracic dermatomes (T3-L2) are the most common site.
  • Allodynia (pain to light touch) reflects the acute neuritis of zoster. Diagnosis is clinical; PCR of vesicle fluid confirms atypical cases.

Why the others are wrong

  • Zosteriform herpes simplex: recurrent HSV can mimic zoster but recurs in a fixed, non-dermatomal location and is not preceded by a banded prodromal pain; PCR distinguishes the two when needed.
  • Allergic contact dermatitis: produces pruritic rather than painful lesions with geometric or linear borders matching the contactant, without a dermatomal pattern or prodromal neuritic pain.
  • Bullous pemphigoid: presents with widespread tense bullae on an urticarial base in older adults and is not unilateral or dermatomal; direct immunofluorescence is positive.
🔒 Free preview limit reached

Keep reading — start your free trial

You've read your 2 free diagnosis previews. Create your free account to unlock the full Herpes Zoster (Shingles) outline — plus all 514 diagnoses, 6,500+ board-style questions, flashcards, and an AI tutor. Your 7-day free trial includes everything, and there's no credit card required.

Start your 7-day free trial → Sign in
Free to start · No credit card · Cancel anytime

Risk factors

  • Age >50 (declining cell-mediated immunity)
  • Immunosuppression: HIV, malignancy (especially hematologic), transplant, chemotherapy, biologics, chronic corticosteroids
  • Stress, trauma
  • Female sex (slightly higher risk)
  • Family history of zoster

Pathophysiology

Primary varicella infection establishes lifelong latency in sensory ganglia. Decline in VZV-specific cell-mediated immunity allows reactivation → viral replication in ganglion → axonal transport down sensory nerve → cutaneous vesicular eruption in dermatomal distribution. Neural damage produces acute neuritis and, in some, chronic postherpetic neuralgia.

Clinical presentation

Symptoms

  • Prodromal pain, burning, paresthesia in dermatomal distribution 1-5 days (occasionally weeks) before rash
  • Acute neuritic pain — sharp, burning, lancinating, allodynia
  • Malaise, low-grade fever, headache
  • Pruritus, tingling in affected area

Signs / physical exam

  • Unilateral grouped vesicles on erythematous base in a dermatomal distribution — does NOT cross midline (except small overlap)
  • Most common dermatomes: thoracic (T3-L2), trigeminal (especially V1 — ophthalmic), cervical, lumbar
  • Lesions progress: erythematous macules/papules → vesicles → pustules → crusts over 7-10 days; complete healing 2-4 weeks (longer in elderly)
  • Zoster ophthalmicus (V1): involvement of forehead, upper eyelid, tip of nose (Hutchinson sign = nasociliary nerve = high risk of ocular involvement)
  • Ramsay Hunt syndrome (CN VII + VIII): facial palsy + vesicles in ear canal/auricle + vertigo + hearing loss + ageusia
  • Disseminated zoster: >20 lesions outside primary dermatome, especially in immunocompromised
  • Zoster sine herpete: dermatomal pain without rash — diagnosis of exclusion, PCR confirms

Classic findings

Painful unilateral vesicular rash respecting the midline in a dermatomal distribution.

Differential diagnosis

  • Herpes simplex (zosteriform HSV) — Recurrent vesicles in fixed location, not strictly dermatomal; PCR/culture differentiates
  • Contact dermatitis — Geometric/linear borders match contactant; pruritus dominant; no prodromal pain
  • Cellulitis — Diffuse warmth, erythema, no vesicles or dermatomal distribution
  • Impetigo — Honey-colored crusts, not dermatomal
  • Bullous pemphigoid — Tense bullae on urticarial base, widespread, older adult; DIF positive
  • Cardiac ischemia or appendicitis (prodromal pain) — Pain without rash in early prodrome can mimic visceral disease; rash emerges 1-5 days later

Diagnostic workup

Diagnostic criteria

Clinical: prodromal pain + unilateral dermatomal vesicular rash; PCR confirms in atypical cases.

Labs

  • Clinical diagnosis sufficient in most cases
  • PCR of vesicle fluid (most sensitive and specific; preferred when confirmation needed)
  • Direct fluorescent antibody (DFA) — rapid
  • Tzanck smear shows multinucleated giant cells (does not distinguish HSV from VZV)
  • Viral culture (low yield)
  • HIV testing in young adults with zoster
  • Workup for underlying malignancy not routinely indicated in immunocompetent adults but consider in disseminated or recurrent disease

Imaging

  • Slit-lamp examination by ophthalmology for any V1 involvement
  • MRI brain if encephalitis, myelitis, or stroke (varicella vasculopathy) suspected

Diagnostic algorithm

ScenarioKey Management Step
Standard zoster <72 hValacyclovir 1 g TID × 7 d + analgesia
Hutchinson sign / V1 involvementAntiviral + urgent ophthalmology
Ramsay Hunt (CN VII)Antiviral + prednisone taper + ENT/audiology
Immunocompromised / disseminatedIV acyclovir + airborne/contact isolation
Postherpetic neuralgiaGabapentin/pregabalin, lidocaine patch, TCA
PreventionRecombinant zoster vaccine (Shingrix) 2 doses, age ≥50
Herpes zoster scenario-based management.

Treatment

First-line

  • Antiviral therapy within 72 hours of rash onset (still beneficial if vesicles still forming or in immunocompromised): valacyclovir 1 g PO TID × 7 days, OR famciclovir 500 mg PO TID × 7 days, OR acyclovir 800 mg PO 5x/day × 7-10 days (valacyclovir/famciclovir preferred due to better bioavailability and dosing)
  • Renal dose adjustment for all antivirals
  • Pain control: acetaminophen, NSAIDs for mild; gabapentin or pregabalin titrated up for moderate-severe neuritic pain; opioids short-term if needed (codeine, tramadol, oxycodone)
  • Tricyclic antidepressants (nortriptyline, amitriptyline) for acute pain and PHN prevention
  • Local: cool compresses, calamine lotion, topical lidocaine 5% patch (after lesions crust)
  • Vaccination: recombinant zoster vaccine (Shingrix) — 2 doses 2-6 months apart, age ≥50, including those with prior zoster (wait until acute episode resolves)

Zoster ophthalmicus

  • Same antiviral as above PLUS urgent ophthalmology referral within 24 hours
  • IV acyclovir if sight-threatening keratitis, iritis, retinal involvement
  • Topical antivirals and steroids only under ophthalmology direction

Ramsay Hunt syndrome

  • Antiviral + oral corticosteroid (prednisone 60 mg/day tapered over 1-2 weeks) — improves facial nerve recovery
  • ENT referral; audiometry

Disseminated / immunocompromised

  • IV acyclovir 10 mg/kg q8h until clinical improvement, then PO antiviral to complete 14 days
  • Airborne + contact isolation (disseminated disease can transmit varicella to non-immune contacts)

Postherpetic neuralgia

  • First-line: gabapentin or pregabalin titrated to effect; topical lidocaine 5% patch; topical capsaicin 8% patch
  • Second-line: TCAs (nortriptyline, amitriptyline), SNRIs (duloxetine, venlafaxine)
  • Third-line: opioids, intrathecal corticosteroids, nerve blocks

Second-line / adjunct

  • Systemic corticosteroids — controversial for typical zoster; may speed acute pain resolution but do not prevent PHN; useful in Ramsay Hunt and severe cases
  • Recombinant zoster vaccine (Shingrix) recommended for immunocompromised adults ≥19 years per CDC ACIP 2022

Complications

  • Postherpetic neuralgia (PHN) — pain persisting >90 days after rash onset; affects 10-18% of all zoster patients, ~30% of those >80 years; antiviral therapy reduces but does not eliminate risk
  • Bacterial superinfection of skin lesions
  • Zoster ophthalmicus: keratitis, uveitis, scleritis, acute retinal necrosis, secondary glaucoma, vision loss
  • Ramsay Hunt syndrome: facial palsy (worse prognosis than Bell's palsy), hearing loss, vertigo
  • CNS: meningoencephalitis, myelitis, varicella vasculopathy → stroke
  • Disseminated visceral zoster (pneumonitis, hepatitis) in immunocompromised
  • Motor zoster (segmental muscle weakness)
  • Transmission of varicella to non-immune contacts (especially neonates, pregnant women, immunocompromised) from active lesions

PANCE pearls

  • Hutchinson sign (vesicles on tip of nose) predicts ocular involvement in zoster ophthalmicus — urgent ophthalmology referral.
  • Antiviral therapy is most effective if started within 72 hours of rash onset, but still consider in ongoing vesicle formation, ocular involvement, immunocompromised, or severe pain.
  • Recombinant zoster vaccine (Shingrix) is preferred over the older live attenuated vaccine (no longer marketed in the US) and is recommended for all adults ≥50 and immunocompromised adults ≥19.
  • Zoster in a young adult should prompt HIV testing.
  • Pre-emptive gabapentin/pregabalin within the first weeks of acute zoster may reduce the incidence and severity of postherpetic neuralgia.

References

  • CDC ACIP 2022 — Use of Recombinant Zoster Vaccine in Immunocompromised Adults Aged ≥19 Years (Anderson et al., MMWR 2022)
  • AAFP 2017 — Herpes Zoster and Postherpetic Neuralgia: Prevention and Management (Saguil et al., Am Fam Physician 2017)
  • Cochrane 2014 — Antiviral Treatment for Preventing Postherpetic Neuralgia (Chen et al., Cochrane Database Syst Rev 2014)

Practice Dermatology questions on FirstPassPA

Turn this outline into retention. 6,500+ board-style questions with an AI tutor that explains every answer — free to start, no card required.

Answer the 2 free questions above → Get today's free question →

Related Dermatology diagnoses

Acne VulgarisRosaceaAtopic Dermatitis (Eczema)Allergic and Irritant Contact DermatitisSeborrheic DermatitisPsoriasisLichen PlanusPityriasis RoseaTinea Infections (corporis, capitis, pedis, cruris, versicolor)Cutaneous CandidiasisScabiesPediculosisImpetigoVerrucae (Warts, HPV)

Differentials & related conditions

Genital Herpes (HSV-2)CellulitisBullous Pemphigoid

Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA or PAEA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants; End of Rotation™ is a program of the Physician Assistant Education Association.