AKT · Dermatology/Infections & infestations

Shingles (herpes zoster)

Reactivation of latent varicella-zoster virus in a dorsal root ganglion

Overview

Reactivation of latent varicella-zoster virus (from prior chickenpox) in a single sensory dorsal-root/cranial ganglion, producing a painful vesicular rash in ONE dermatome that does not cross the midline. Key exam points are early antivirals, the ophthalmic (Hutchinson sign) and otic (Ramsay Hunt) danger zones, and post-herpetic neuralgia.

Recognise

Prodromal burning/tingling pain in a dermatome, then a band of grouped erythematous papules → vesicles → pustules/crust, UNILATERAL and not crossing the midline
Most often thoracic; postherpetic neuralgia (pain persisting >3 months) is the commonest complication, especially in the elderly
Infectious (causes chickenpox in the non-immune) until the lesions crust

Red flags

Ophthalmic zoster with vesicles on the nose tip/side (HUTCHINSON SIGN) → eye involvement → urgent ophthalmology; Ramsay Hunt (facial palsy + ear vesicles) → see neurology; disseminated zoster in the immunocompromised

Differentials & how to tell them apart

Herpes simplexrecurrent at the same non-dermatomal site, smaller cluster

Impetigogolden honey crust, not dermatomal or preceded by neuralgic pain

Contact dermatitisitchy not neuralgic, matches contact area, not a single dermatome

Cellulitisspreading hot erythema without grouped vesicles or dermatomal pattern

Clinical image

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Shingles (herpes zoster) — clinical imagesDermNet

Investigations

Clinical diagnosis. Swab (viral PCR) only if atypical/immunocompromised. Assess for eye (ophthalmic division) and ear (Ramsay Hunt) involvement.

Management

Oral antiviral (aciclovir) started within 72 h + analgesia

1Start an oral antiviral (aciclovir/valaciclovir/famciclovir) — ideally within 72 hours of rash onset (or while new lesions are still appearing) — plus analgesia; keep lesions covered (infectious until crusted).Gate: Vesicles on the tip/side of the nose (HUTCHINSON SIGN) mean nasociliary/eye involvement (ophthalmic zoster) → urgent ophthalmology; and facial palsy with vesicles in the ear = Ramsay Hunt → urgent antiviral + steroid (neurology) — these danger zones change the referral
2Postherpetic neuralgia → amitriptyline, gabapentin/pregabalin, or capsaicin; immunocompromised/disseminated/ophthalmic → IV aciclovir / specialist; offer the shingles vaccine for prevention.

Oral aciclovir / valaciclovir / famciclovir — start within 72 h of rash onset (or while new vesicles still forming) — reduces severity and postherpetic neuralgia risk

Analgesia (incl. amitriptyline/gabapentin for neuralgic pain) — for acute pain and postherpetic neuralgia

Shingles vaccine — prevention in older adults

Key points

Dermatomal, unilateral, painful vesicles that respect the midline = shingles → antiviral within 72 h. Hutchinson sign (nose) = eye; ear vesicles + facial palsy = Ramsay Hunt. (Also an Infection-page topic — cross-reference, don't duplicate.)

Monitor & prognosis

Rash crusting, pain/postherpetic neuralgia, eye/ear complications.

Usually self-limiting; postherpetic neuralgia is the main morbidity in older patients.

Source: NICE CKS Shingles