When to Bring a Febrile Child to the Emergency Department
Any infant younger than 3 months with a rectal temperature ≥38.0°C (100.4°F) requires immediate emergency evaluation, regardless of how well they appear. 1, 2
Age-Based Temperature Thresholds for Emergency Evaluation
Infants Under 3 Months (Highest Risk)
- Emergency evaluation required for any fever ≥38.0°C (100.4°F) 1, 2
- This age group has immature immune systems and only 58% of those with bacteremia or meningitis appear clinically ill 1
- Even well-appearing infants in this age range warrant urgent assessment due to risk of serious bacterial infection (SBI) including meningitis, bacteremia, and urinary tract infections 1
Infants 3-6 Months
- Seek emergency care if temperature ≥39.0°C (102.2°F) 3
- This threshold reflects increased risk for occult bacteremia and other serious infections 1
Children 6 Months to 3 Years
- Temperature ≥39.5°C (103.1°F) warrants medical evaluation 1
- At this temperature, the prevalence of occult pneumococcal bacteremia increases to approximately 10% in children with elevated white blood cell counts 1
- Temperature ≥40.0°C (104°F) should prompt emergency evaluation 1, 4
Critical Warning Signs That Override Temperature Thresholds
Bring the child to emergency immediately if ANY of these are present, regardless of temperature: 1, 3
- Toxic or ill appearance (lethargy, poor eye contact, inconsolability)
- Difficulty breathing or rapid breathing
- Persistent vomiting or inability to keep fluids down
- Signs of dehydration (decreased urination, dry mucous membranes, no tears)
- Stiff neck or severe headache
- Petechial or purpuric rash
- Seizure activity
- Altered mental status or extreme irritability
- Hypothermia (temperature below normal despite fever history)
Important Clinical Nuances
The "Well-Appearing" Paradox
- Clinical appearance alone is unreliable in young infants—only 58% of those with serious bacterial infections appear ill 1
- Never rely solely on how "good" an infant under 3 months looks; the temperature threshold of 38.0°C (100.4°F) is absolute 1, 2
Antipyretic Use Can Mask Severity
- Recent acetaminophen or ibuprofen use may lower measured temperature and create false reassurance 1
- Ask about antipyretic administration in the previous 4 hours 1
- If fever was documented at home as ≥38.0°C (100.4°F) in an infant under 3 months, emergency evaluation is still required even if the temperature is normal on arrival 1
Temperature Measurement Matters
- Rectal temperature is the gold standard for infants and young children 2, 3, 5
- Home thermometer accuracy should be questioned 1
- Infrared ear thermometers are not consistently reliable in children under 3 years 5
Post-Pneumococcal Vaccine Era Considerations
While the introduction of conjugate pneumococcal and Haemophilus influenzae type B vaccines has dramatically reduced rates of occult bacteremia (from historical rates of 2.8% down to approximately 1.45%), the risk has not been eliminated 1. The age-based temperature thresholds remain valid because:
- Serious bacterial infections still occur in vaccinated children 1
- Not all children are fully immunized 1
- Vaccine coverage doesn't include all bacterial pathogens 1
Common Pitfalls to Avoid
- Don't assume fever height correlates with illness severity in older children—a child with 40°C (104°F) may have a benign viral illness, while serious infections can present with lower fevers 4, 6
- Don't be falsely reassured by a child's ability to tolerate antipyretics—improvement with acetaminophen doesn't rule out serious infection 7, 6
- Don't delay evaluation in young infants hoping the fever will resolve—the one death in a large hyperpyrexia study was attributed to delayed medical care 4
- Don't forget that viral and bacterial infections can coexist—presence of viral symptoms doesn't exclude serious bacterial infection 1
Parental Monitoring Capacity
Emergency evaluation is also warranted if caregivers cannot reliably monitor the child or return for reassessment within 12-24 hours, regardless of temperature level 1.