🧭 When to suspect

Suspect chickenpox in anyone with a brief prodrome of fever, malaise and headache (often minimal or absent in young children), followed by a characteristic, intensely itchy rash.

The rash:

• Evolves through macules → papules → vesicles (the classic "dew drops on a rose petal") → crusts

• Appears in successive crops so that all stages coexist

• Typically begins on the face and trunk before spreading, sparing the limbs relatively

A history of contact with chickenpox or shingles supports the diagnosis.

The diagnosis is usually straightforward; the harder part is to:

• Identify the three high-risk groups in whom varicella can be life-threatening (neonates, pregnant women and the immunocompromised)

• Recognise the serious complications (pneumonia, encephalitis, severe bacterial infection)

Most healthy children need only supportive care.

Two system changes now frame every consultation:

• From 1 January 2026 the combined measles, mumps, rubella and varicella (MMRV) vaccine replaced MMR in the routine childhood schedule (doses at 12 and 18 months), so milder breakthrough disease in part-vaccinated children will become a more common presentation

• Chickenpox became a notifiable disease in England in 2025

Stage	Features and timing
Incubation	10–21 days from exposure (commonly 14–16 days).
Prodrome	1–2 days of fever, malaise and headache – often minimal or absent in young children.
Rash	• Macules → papules → vesicles → crusts, in crops so all stages coexist • Starts on face/scalp and trunk, spreads centrally, sparser on the limbs • Mucous membranes may be involved
Infectious period	From 1–2 days before the rash until all lesions have crusted (usually ~5 days from onset; prolonged if immunosuppressed).
Return to school/work	Once all lesions have crusted over.

Source: UKHSA Green Book (chapter 34) · UKHSA and NHS England (MMRV programme)

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