Fever of unknown origin

Any person, 4 weeks to 15 years, presenting with a fever or history of fever of 38°C and above, without focus.

History prompts, signs and symptoms

These are not exhaustive lists. Maintain an open mind and be aware of cognitive bias.

Red flags

Recognise: identify indicators of actual or potential clinical severity and risk of deterioration.

Respond: carefully consider alternative ECAT protocol. Escalate as per clinical reasoning and local CERS protocol, and continue treatment.

Clinical assessment and specified intervention (A to G)

If the patient has any Yellow or Red Zone observations or additional criteria (as per the relevant NSW Standard Emergency Observation Chart), refer and escalate as per local CERS protocol and continue treatment.

Position

Assessment	Intervention
General appearance/first impressions	Position of comfort

Airway

Assessment	Intervention
Patency of airway	Maintain airway patency Consider airway opening manoeuvres and positioning

Breathing

Assessment	Intervention
Respiratory rate and work of breathing Auscultate chest (breath sounds) Oxygen saturation (SpO2)	Assist ventilation as clinically indicated Apply oxygen to maintain SpO2 over 93% If wheeze present, consider bronchiolitis (suspected) protocol or wheeze (including viral-induced or suspected asthma) protocol If barking cough or stridor present, consider croup-like illness protocol

Circulation

Assessment	Intervention
Perfusion (capillary refill, skin warmth and colour) Heart rate Blood pressure Cardiac rhythm	Assess circulation Attach cardiac monitor if BP/HR are within the Yellow or Red Zones, or where clinically relevant, e.g. irregular pulse, palpitations, syncope, shock, respiratory compromise, cardiac history or clinical concern Consider 12 lead ECG
IVC and/or pathology	Insert IV cannula, if trained and clinically indicated If unable to obtain IV access, consider intraosseous, if trained See pathology section
Signs of shock: tachycardia and CRT 3 seconds and over and/or abnormal skin perfusion and/or hypotension	If signs of shock present, give sodium chloride 0.9% at 20 mL/kg IV/intraosseous bolus, once only, maximum dose 1000 mL and consider sepsis (suspected) protocol

Disability

Assessment	Intervention
AVPU	If AVPU shows reduced level of consciousness, continue to assess GCS, pupillary response and limb strength
GCS, pupillary response and limb strength	Obtain baseline and repeat assessment as clinically indicated
Pain	Assess pain. If indicated, give early analgesia as per analgesia section then resume A to G assessment

Exposure

Assessment	Intervention
Temperature	Measure temperature If unwell or systemic features, consider sepsis (suspected) protocol Hypothermia or temperature instability may occur in infants under 3 months
Head-to-toe inspection, including posterior surfaces	Check and document any abnormalities Urgent management is required for patients who are unwell with petechial or purpuric rash. Switch to sepsis (suspected) protocol

Fluids

Assessment	Intervention
Hydration status	Assess fluids, in and out. Document on fluid balance chart. Include gastrointestinal losses
Nausea and/or vomiting	If present, see nausea and/or vomiting section

Glucose

Assessment

Intervention

BGL

Measure BGL. See medication table for 40% glucose gel dosing If BGL between 2 mmol/L and 3 mmol/L and NOT symptomatic (Yellow Zone criteria): give quick-acting carbohydrate: Up to 12 months: milk feed and/or 40% glucose gel buccal 12 months and over: sugary soft drink or fruit juice or 40% glucose gel buccal reassess BGL in 15–30 minutes and repeat treatment until BGL over 3 mmol/L If BGL less than 2 mmol/L OR symptomatic (Red Zone criteria) OR unable to tolerate oral glucose: give 40% glucose gel buccally in incremental doses, as tolerated, while establishing IV access give 10% glucose, 2 mL/kg by slow IV injection once only if IV access delayed, give: Up to 25 kg: glucagon 0.5 mg IM, once only 25 kg and over: glucagon 1 mg IM, once only reassess BGL in 15 minutes Once stabilised, give patient long-acting carbohydrate and continue to check BGL hourly, or as clinically indicated

Focused assessment

Consider dehydration focused assessment.

Precautions and notes

• Antipyretics can be given to alleviate the discomforts of fever.
• Febrile convulsions are generally benign and do not require investigations or management.
• Most episodes of fever in children are mild or self-limiting, however they can be challenging to distinguish from serious infection.
• The degree of the fever is not a reliable predictor of serious illness.
• If tachycardia and/or respiratory distress remain despite analgesia, consider the potential for serious illness and escalate care as required.
• Infants less than 3 months old may not have characteristic signs of serious illness.
• Pathology is often not required in infants over 3 months without signs of systemic illness.

Interventions and diagnostics

Analgesia

If pain score 1–6 (mild–moderate):

Give paracetamol 15 mg/kg orally once only, maximum dose 1000 mg

and/or ibuprofen, if 3 months and over, 10 mg/kg orally once only, maximum dose 400 mg

If severe pain present, give analgesia and escalate as per local CERS protocol.

Consider non-pharmacological pain relief (appendix).

---

Nausea and/or vomiting

If nausea and/or vomiting is present and over 6 months give:

---

Procedural analgesia

For pain relief required during procedures only, not used to replace appropriate analgesia.

Sucrose 24%

• 1–18 months: give 1–2 mL orally per procedure
• Maximum dose:
  • 1–3 months: up to 5 mL in 24 hours
  • 3–18 months: up to 10 mL in 24 hours.

Repeat as needed up to the maximum dose.

---

Radiology

Radiology will depend on the working diagnosis. It needs to be requested by a medical or nurse practitioner. If there is concern for urgent radiology, escalate as per local CERS protocol.

---

Pathology

• Urinalysis
  • Patient who can void in the toilet: mid-stream urine
  • Patient who is not toilet trained: clean catch or catheter urine
  • Send for MC&S. Keep the sample refrigerated if transport is delayed
  • Refer to urine sampling appendix for further detail
• Seriously unwell person: FBC, UEC, glucose, CRP, VBG with lactate, blood cultures

Medications

The patient’s weight is mandatory for calculating fluid and medication doses.

The Broselow Tape or APLS weight table (appendix) can be used only in circumstances where the patient cannot be weighed.

The shaded sections in this protocol are only to be used by registered nurses who have completed the required education.

Medications with contraindications or requiring dose adjustment are marked:

• ^H for patients with known hepatic impairment
• ^R for patients with known renal impairment.

Escalate to medical or nurse practitioner.

Evidence informed	Information was drawn from evidence-based guidelines and a review of latest available research. For more information, see the development process.
Collaboration	This protocol was developed by the ECAT Working Group, led by the Agency for Clinical Innovation. The group involved expert medical, nursing and allied health representatives from local health districts across NSW. Consensus was reached on all recommendations included within this protocol.
Currency	Due for review: Jan 2026. Based on a regular review cycle.
Feedback	Email ACI-ECIs@health.nsw.gov.au