When to Take a 5-Month-Old Infant to the Hospital for Fever
A mother should take her 5-month-old infant to the hospital for a rectal temperature of 39°C (102.2°F) or higher, especially if the baby appears ill or has no obvious source of infection.
Temperature Thresholds by Age
Temperature thresholds for seeking medical attention vary by age:
- 0-3 months: Any fever ≥38.0°C (100.4°F) requires immediate medical attention 1
- 3-6 months: Temperature ≥39.0°C (102.2°F) warrants medical evaluation, especially without an obvious source of infection 1
Risk Factors That Lower the Threshold for Hospital Visit
Even with lower temperatures, seek immediate medical attention if your 5-month-old has:
- Appears ill, lethargic, or difficult to wake
- Decreased feeding or poor fluid intake
- Persistent crying or unusual irritability
- Rash, especially one that doesn't blanch when pressed
- Difficulty breathing or rapid breathing
- Signs of dehydration (dry mouth, no tears when crying, decreased urination)
- History of febrile seizures or underlying medical conditions
Temperature Measurement Considerations
- Rectal temperature is the most accurate method for infants under 6 months 2
- Axillary (armpit) temperatures are typically 0.7°C (1.3°F) lower than rectal temperatures and may miss fevers (73% sensitivity) 2
- Parental palpation alone is unreliable for detecting fever (sensitivity 81%, specificity 82%) 3
Timing Considerations
- Fevers occurring after vaccinations are generally less concerning but still warrant attention if they reach the thresholds above 4
- Fevers occurring during office hours may be managed by calling your pediatrician first, while after-hours fevers may require emergency evaluation 4
Hypothermia Concerns
Hypothermia (temperature below 36.0°C/96.8°F) in infants can actually be more concerning than fever and requires immediate medical attention, as it may indicate serious bacterial infection or other significant pathology 5, 1.
Key Points to Remember
- Use a reliable thermometer rather than just touch to determine fever 3
- Dress your infant in one more layer than an adult would wear in the same environment 6
- Maintain indoor ambient temperature of at least 23°C (73.4°F) to prevent hypothermia 6
- When in doubt about your infant's condition, it's always safer to seek medical attention
Remember that infants under 3 months with fever have a significantly higher risk of serious bacterial infections, while 5-month-olds have a more developed immune system but still require prompt evaluation for high fevers.