Fever in Under 5s

NICE guideline [NG143] Fever in under 5s: assessment and initial management. Last updated: Nov 2021.

Article Last Updated:23/09/2025

Diagnosis Guidelines

Detection of Fever

Recommended methods:

<4 w/o → axilla measurement with electronic therometer
4 w/o – 5 y/o → axilla measurement (electronic / chemical dot therometer) or infra-red tympanic measurement

Do not routinely use the oral and rectal routes to measure body temperature of 0-5 y/o children.

Important Fever Causes

NICE specifically mentioned the following causes of fever in under 5s:

Cause of fever	When to consider
Meningococcal disease and bacterial meningitis	Any of the following: Non-blanching rash Bulging fontanelle ↓ Level of consciousness Convulsive status epilepticus Capillary refill time ≥3 sec
Herpex simplex encephalitis	Any of the following Focal neurological signs Focal seizure ↓ Level of consciousness
Pneumonia	Any of the following: Tachypnoea Nasal flaring Chest indrawing Cyanosis SpO₂ <95% Crackles on auscultation
UTI	Features that increase the likelihood of UTI: Dysuria / frequent urination Malodorous / darker / cloudy urine Frank haematuria New bedwetting Reduced fluid intake Abdominal pain / loin tenderness / suprapubic tenderness Shivering Capillary refill time >3 sec
Septic arthritis / osteomyelitis	Any of the following: Limb / joint swelling Not using an extremity Non-weight bearing
Kawasaki disease	Fever for >5 days, and possible additional features (CRASH): Conjunctival injection (bilateral without exudate) Rash Adenopathy (cervical lymphadenopathy) Strawberry tongue Hands and feet oedema

Work-Up and Management Guidelines

Traffic Light System

	Green (low risk)	Amber (intermediate risk)	Red (high risk)
Colour	Normal colour	Pallor	Pale / mottled / ashen / blue
Activity	Responds normally to social cues Content / smiles Stays awake or awakens quickly Strong normal cry / not crying	Not responding normally to social cues No smile Wakes only with prolonged stimulation Decreased activity	No response to social cues Appears ill Does not wake / not stay awake if roused Weak / high-pitched / continuous cry
Breathing	n/a	Nasal flaring Tachypnoea (>50/min in 6-12 m/o, >40/min in >12 m/o) SpO₂ ≤95% Crackles on auscultation	Grunting Tachypnoea (>60/min) Chest indrawing
Circulation	n/a	Tachycardia (>160bpm in <12 m/o, >150bpm in 12-24 m/o, >140bpm in 2-5 y/o) Capillary refill time ≥3 sec Dry mucous membranes Reduced urine output Poor feeding in infants	Reduced skin turgor
Temperature	n/a	3-6 m/o + ≥39°C Fever for ≥5 days	<3 m/o + ≥38°C
Other	n/a	Rigors Swelling of a limb / joint Non-weight bearing / not using an extremity	Non-blanching rash Bulging fontanelle Neck stiffness Focal neurological signs Focal seizures Status epilepticus

Assessment and Work-Up

Non-Specialist

Any red features → refer urgently to paediatric specialist
Any amber features → safety netting with follow-up or refer to paediatric specialist
No amber or red features → care at home with safety netting

Specialist

<3 m/o

Investigations	Indications
FBC Blood culture CRP Urine testing (clean catch method if possible)	Perform routinely (all patients)
Chest X-ray	Only if respiratory signs are present
Stool culture	Only if diarrhoea is present
Lumbar puncture	Almost routinely… Only in the following: < 1 m/o (routinely) 1-3 m/o who appear unwell WBC <5×10⁹/L or >15×10⁹/L

3 m/o – 5 yo

Traffic light group	Investigations
Red (any)	Perform the following routinely: Blood tests (FBC, blood culture, CRP) Serum electrolyte and blood gas Urine testing (clean catch method if possible) Chest X-ray Lumbar puncture
Amber (any)	Perform the following routinely: Blood tests (FBC, blood culture, CRP) Urine testing (clean catch method if possible) Other conditional tests: Chest X-ray if >39°C and WBC >20×10⁹/L Lumbar puncture (if <1 y/o)
Green	Perform the following routinely: Examination for pneumonia features Urine testing (clean catch method if possible) Do NOT perform the following routinely: Blood tests (FBC, blood culture, CRP) Chest X-ray

Traffic light group

Investigations

Red (any)

Perform the following routinely:

Blood tests (FBC, blood culture, CRP)
Serum electrolyte and blood gas
Urine testing (clean catch method if possible)
Chest X-ray
Lumbar puncture

Amber (any)

Perform the following routinely:

Blood tests (FBC, blood culture, CRP)
Urine testing (clean catch method if possible)

Other conditional tests:

Chest X-ray if >39°C and WBC >20×10⁹/L
Lumbar puncture (if <1 y/o)

Green

Perform the following routinely:

Examination for pneumonia features
Urine testing (clean catch method if possible)

Do NOT perform the following routinely:

Blood tests (FBC, blood culture, CRP)
Chest X-ray

Management (By Specialist)

Management should be guided by the working diagnosis and investigation findings. The following are important points outlined by NICE.

Antibiotic Therapy

IV antibiotic is indicated if:

Fever, and
Shocked / unrousable / signs of meningococcal disease

Choice of antibiotics (until culture results are available):

<3 m/o → 3rd generation cephalosporin (ceftriaxone / cefotaxime) + amoxicillin / ampicillin (to cover Listeria)
Otherwise → 3rd generation cephalosporin (ceftriaxone / cefotaxime)

Other Management

Suspected sepsis (fever + shock):

0.9% NaCl bolus of 10mL/kg, and
IV antibiotics

Suspected herpes simplex encephalitis:

IV aciclovir

Antipyretics are only indicated to relieve distress from the fever (but NOT just to reduce body temperature):

Paracetamol / ibuprofen
Continue as long as the child appears distressed

Oxygen therapy is indicated in:

SpO₂ <92% + signs of shock
Consider if SpO₂ >92% as clinically indicated

References

Original Guideline

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