Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
!
Non-blanching or systemically dangerous rash
A child with fever plus non-blanching petechiae or purpura, shock, reduced consciousness, neck stiffness, seizures, respiratory compromise, severe focal pain, extensive blistering or mucosal loss may have meningococcal sepsis, another invasive infection, encephalitis or a severe cutaneous adverse reaction.
Action: Use an ABCDE assessment, treat suspected sepsis or meningococcal disease immediately according to age-specific guidance, isolate appropriately and transfer urgently; investigations and the search for a named exanthem must not delay antibiotics, resuscitation or airway and skin-failure care.
Synopsis
Use timing, distribution and associated features to distinguish common childhood viral eruptions, identify sepsis and inflammatory mimics, choose targeted testing, and apply notification, isolation and high-risk-contact actions.
Describe blanching, lesion type, onset site, direction of spread and relationship to fever before naming an exanthem; pattern supports but rarely proves the virus.
Measles causes fever, cough, coryza and conjunctivitis followed by a descending maculopapular eruption; call ahead, isolate and notify the suspected case without waiting for laboratory confirmation.
Rubella is often mild with post-auricular or suboccipital nodes, but pregnancy exposure has urgent fetal implications and requires health-protection advice.
Key red flags
Non-blanching purpura, toxic appearance, altered consciousness, neck stiffness, respiratory distress, shock, severe dehydration, painful skin, blisters or mucosal erosion, focal neurology, a very young infant, immunocompromise, pregnancy exposure or fever lasting five days with Kawasaki or PIMS-TS features changes the case from routine exanthem care.
Measles
High fever, cough, coryza and conjunctivitis precede Koplik spots and a confluent maculopapular eruption that begins behind ears or on face and spreads downward.
Investigation priorities
01
ABCDE and age-specific observationsFirst step
Detect shock, hypoxia, encephalopathy and dehydration before classifying morphology.
Management branches
Immediate-danger routeTreat physiology before pattern
The child is toxic, shocked, neurologically abnormal, severely dehydrated or has non-blanching purpura or mucosal skin failure.
Perform ABCDE assessment, obtain senior paediatric help and isolate where an airborne or contact-transmitted infection is plausible.
Give age-specific sepsis and meningococcal treatment, fluids, oxygen and airway support without waiting for rash evolution or test results.
Key medicines
Paracetamol for fever-related distressUse the child's age- or weight-appropriate licensed oral dose and interval shown in the current product information; do not exceed the stated 24-hour maximum and check combination cold remedies for duplicate paracetamol.
Aciclovir for high-risk or complicated varicellaUse only after urgent specialist assessment, with route and dose adjusted for age, weight, immune status, renal function and time from rash onset; severe, neonatal or immunocompromised disease generally requires intravenous paediatric treatment.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.