Reasoning GP · Algorithm · 1-page summary
Rash with fever in a child
For: children with fever and a rash in primary care; the NICE traffic light is validated under 5, same principles to 16. Not for: fever without rash (fever in children algorithm); immunocompromised children follow their specialist pathway.
Core rule: look at the whole child before the rash. A non-blanching rash with fever is meningococcal disease until proved otherwise — and the glass test cannot exclude it.
0Stop — call 999 now — do not delay transfer
- Non-blanching rash with fever, or an ill child with a rash → 999; meningococcal disease strongly suspected → IM/IV benzylpenicillin or ceftriaxone unless it delays transfer (dose per NICE/SPC (children: BNFC)).
- Shock (mottled, cold hands and feet, weak pulse), suspected meningitis, seizure, respiratory compromise → 999
- iGAS features — pain out of proportion, rapidly spreading redness, toxic child → 999
1Triage — NICE NG143 traffic light
| Colour | Action |
|---|---|
| Red | Urgent paediatric assessment (generally ≤2 h); 999 if life-threatening |
| Under 3 months | Temperature 38°C or more → red |
| Amber | Face-to-face; same-day paediatrics if concerning, else safety-net and review |
| Green | Home with written safety-net |
2Screen
- Fever for 5 days or more with red eyes, lips, rash, swollen hands or feet → Same-day paediatrics (Kawasaki)
- Blisters, skin pain, mucosal involvement (eczema herpeticum, SJS) → Same-day
- Complicated chickenpox, neonate or immunosuppressed with chickenpox or measles → Same-day
- Unexplained petechiae, pallor, hepatosplenomegaly → immediate paediatric assessment
3Assess
☐ Temperature, HR, RR, SpO₂, capillary refill, hydration ☐ Undress fully; check conjunctivae, palms, soles, mouth ☐ Blanching or not ☐ Vaccination (MMR/MMRV) ☐ Contacts, pregnant household members ☐ Urine if under 5 with no source
Do not: delay transfer for tests, or rely on the glass test.
4Classify
- Measles — cough, coryza, conjunctivitis, Koplik spots, rash from the face down → notify, isolate.
- Scarlet fever — sore throat, sandpaper rash, strawberry tongue → treat, notify.
- Chickenpox — itchy vesicles in crops → supportive; no NSAIDs.
- HFMD · slapped cheek · roseola — well child → supportive.
- Kawasaki — fever for 5 days or more + mucocutaneous signs → same-day.
- Uncertain — reassess; any doubt about a non-blanching rash → 999.
5Treat today — doses: NICE/SPC, BNFC, local formulary
- Scarlet fever: phenoxymethylpenicillin for 10 days; allergy → macrolide per UKHSA.
- Chickenpox: paracetamol, fluids, emollient; aciclovir not routine in healthy children.
- Antipyretics for distress only; not both at once; no tepid sponging.
- Notify measles, scarlet fever, iGAS, rubella, meningococcal on suspicion.
6Exclusion (UKHSA)
- Chickenpox at least 5 days and until all spots crusted · measles 4 days from rash · scarlet fever 24 hours after antibiotics.
- HFMD, slapped cheek, roseola: none if well. Pregnant contacts → midwife or GP.
7Never reassure by
- A rash that blanches in an ill child.
- A negative glass test.
- A fall in temperature after paracetamol or ibuprofen.
- Absence of neck stiffness in an infant.
- "Viral rash" when fever has lasted 5 days or more.
- Ibuprofen in chickenpox.
8Safety-net — verbal and written
999 “Call 999 if the rash does not fade when a glass is pressed on it, your child is floppy, drowsy or hard to wake, has a fit, struggles to breathe, or has cold hands and feet with pale or mottled skin.” Same day “Contact us the same day if the fever lasts 5 days or more, your child is not drinking, or chickenpox spots become red, hot and very painful.”
Remote consultation: any non-blanching rash or red feature converts to face-to-face or emergency care.
✓Safe to manage in primary care only if — all five, documented
No red feature; rash blanches; child looks well
Whole skin examined, observations recorded
Diagnosis named; notified if required
Exclusion and vulnerable contacts advised
Written safety-net; review if amber
Summary of the full Reasoning GP rash with fever in a child algorithm, which holds the detail and evidence. Sources: NICE NG143; NICE NG240; UKHSA children and young people settings guidance, scarlet fever and measles guidance; NICE CKS. Clinical reference — check doses in the SPC and your local formulary.