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Paediatrics

Chickenpox

Primary varicella-zoster infection causes successive crops of itchy vesicles that crust, then establishes lifelong latency in sensory ganglia and can later reactivate as shingles.

In a nutshell

Chickenpox is an itchy vesicular eruption in crops, with lesions at different stages at the same time. It is usually mild in healthy children but can be severe in neonates, pregnancy and immunocompromise. The urgent tasks are to identify high-risk hosts, prevent transmission, treat complications and arrange current UK post-exposure management.

Classic presentation

A child with mild fever and an itchy rash of macules, vesicles and crusts of different ages, usually starting on the trunk or face.

Key points

  • Lesions of different ages are the key diagnostic clue.
  • Infectiousness runs from about 2 days before the rash until all lesions have crusted.
  • Avoid ibuprofen unless directed by a doctor; do not give aspirin to children under 16.
  • Red, hot or painful skin, breathlessness, neurological symptoms, dehydration or severe systemic illness need urgent review.
  • Pregnant, neonatal and immunocompromised contacts need urgent UKHSA/specialist assessment after exposure.
  • In England, chickenpox is currently a routine notifiable disease.
  • MMRV is offered at 12 and 18 months in the current UK childhood schedule.

First-line investigation

Usually none: diagnose clinically when the rash is typical; use lesion PCR or targeted testing when atypical, severe or high-risk.

Management

Recognise the pattern and assess host risk

  • Confirm the characteristic crops and immediately ask about pregnancy, neonatal age, immunosuppression, vaccination, exposure and complications.1,2

Support the uncomplicated child

  • Give fluids, paracetamol and antipruritic advice; avoid ibuprofen unless specifically directed and do not give aspirin to children under 16.2,4

Escalate severe disease or vulnerable contacts

  • Urgently involve paediatric, obstetric, infectious-diseases or immunology services for neonates, pregnancy, immunocompromise, severe/disseminated disease, pneumonitis, encephalitis or significant exposure.1,3,2

Use current antiviral and PEP pathways

  • Use specialist-directed antiviral treatment and risk-group-specific post-exposure prophylaxis, checking the current UKHSA guidance and BNF rather than relying on an old VZIG rule.3,1,4

Notify and prevent future cases

  • Report suspected cases through the current England notification route, advise exclusion until crusting, and check eligibility for the current MMRV schedule.5,6,2

Exam traps

  • Chickenpox lesions are polymorphic because they appear in crops; a uniform maculopapular rash suggests another diagnosis.
  • Crusting, not simply resolution of fever, defines the usual exclusion period.
  • Shingles is reactivation of latent varicella-zoster virus; exposure to shingles can cause chickenpox in a susceptible person.
  • VZIG is not a blanket answer for every exposed patient: use the current UKHSA risk-group and supply pathway.
  • The UK schedule changed to MMRV from January 2026.

Illustrations

Chickenpox lesions at different stagesClinical photograph of the back showing the typical centripetal chickenpox eruption with papules, vesicles, pustules and crusted lesions present simultaneously.F malan, Wikimedia Commons · CC-BY-SA-3.0
Dermatomal distribution of shinglesDiagram illustrating varicella-zoster virus latency in the dorsal root ganglion and its reactivation along a single sensory dermatome as shingles.PassFinals · original

Key sources

  1. UKHSA: Varicella, the Green Book chapter 34 (Current UK immunisation and varicella public-health guidance, including the 2026 MMRV schedule and high-risk disease context.)Updated 14 Apr 2026
  2. NHS: Chickenpox (Current NHS information on presentation, infectious period, self-care, red flags and MMRV vaccination.)Updated 31 Jan 2025
  3. UKHSA: Guidelines on post-exposure prophylaxis for varicella or shingles (Current UK post-exposure guidance for susceptible high-risk contacts, including pregnancy, immunosuppression and neonatal risk.)
  4. BNF online (Current UK prescribing information for antipyretics, antipruritics and antiviral prescribing checks.)
  5. UKHSA: Notifiable diseases and how to report them (Current England notification process and list, including chickenpox as routine, measles as urgent, and rubella and scarlet fever as routine.)Updated 19 May 2026
  6. NHS: MMR and MMRV vaccine (Current NHS childhood MMRV schedule and catch-up information.)

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.