Herpes zoster

By Dr. Pascal Bafteh · last updated 09/2026

Definition and Pathogenesis

Herpes zoster is caused by the reactivation of the varicella-zoster virus, a DNA virus from the family Herpesviridae. After a primary infection (varicella), the virus persists latently in the spinal ganglia and can be reactivated when cellular immunity wanes.

Epidemiology and Risk Factors

The disease occurs more frequently in:

• older age (>60 yrs)
• immunosuppression
• HIV infection

Clinical Presentation

Typical is a unilateral dermatomal rash with grouped vesicles on an erythematous base. Often, burning pain precedes the skin changes by several days.

Most commonly affected dermatomes are in the area of:

• thorax (approx. 50–70 % of cases, especially Th3–L3)
• trigeminal nerve (V1 > V2 > V3) — high ocular complication rate with V1 involvement

Special Forms

Zoster ophthalmicus results from involvement of the first trigeminal branch and can lead to keratitis. The appearance of lesions on the tip of the nose is called Hutchinson sign (involvement of the nasociliary nerve) and indicates ocular involvement.

• In case of ocular involvement (zoster ophthalmicus, V1) MANDATORY ophthalmology consult — risk of keratitis, iridocyclitis, acute retinal necrosis (ARN), vision loss.
• In case of ear involvement (zoster oticus / Ramsay-Hunt syndrome) MANDATORY ENT consult — risk of peripheral facial nerve palsy, sensorineural hearing loss, vestibulopathy/vertigo.

Complications

The most common complication is post-zoster neuralgia, classically defined as persistent pain lasting longer than 4 weeks after resolution of the skin lesions; the German S2k guideline and the IASP set the cut-off at > 3 months after rash onset (30–90 days = subacute zoster neuralgia). Further possible complications include bacterial superinfection of the lesions and — depending on the affected nerve — peripheral facial nerve palsy, sensorineural hearing loss and iridocyclitis/uveitis.

• Zoster meningoencephalitis (rare, ~0.1–0.5 %): usually 1–2 weeks after rash onset. Clinical: headache, fever, meningismus, confusion. Diagnosis: VZV PCR in CSF. Therapy: aciclovir i.v. 10 mg/kg body weight every 8 h for 14–21 days. Increased risk: immunosuppressed, multidermatomal zoster, trigeminal involvement.

Differential diagnoses

• Herpes simplex labialis
• Phlegmon
• Varicella (chickenpox)
• Eczema herpeticum
• Impetigo
• Phytophotodermatitis
• Erysipelas

Sources (selection)

1. NEJM
2. Plewig 2018 Braun-Falco S.120

More viral skin infections

• Mpox
• Erythema infectiosum (fifth disease)
• Varicella (chickenpox)

Note: This page is intended for medical education and does not replace diagnosis or treatment decisions in individual cases. Treatment and follow-up content is available in the app.