pyrexia in children

Last edited 12/2021 and last reviewed 02/2023

Pyrexia is a physiological response to illness, and may be is due to an increase in the set point of temperature in the hypothalamic regulatory centre. Older children suffer higher fevers than neonates in whom mechanical thermogenesis by shivering is limited.

There is little evidence that reducing fever improves the outcome of childhood infections. It is not clear if fever act as a defence against infection but what evidence there is suggests it does.

Some pathogens such as Strep.pneumoniae may be directly inhibited by fever.

Notes (1):

• NICE state that:
  
  
  • recognise that children younger than 3 months with a temperature of 38°C or higher are in a high-risk group for serious illness
    
    
  • recognise that children aged 3-6 months with a temperature of 39°C or higher are in at least an intermediate-risk group for serious illness
    
    
• do not use duration of fever to predict the likelihood of serious illness. However, children with a fever lasting 5 days or longer should be assessed for Kawasaki disease
• think "Could this be sepsis?" and refer to the NICE guideline on sepsis: recognition, diagnosis and early management if a child presents with fever and symptoms or signs that indicate possible sepsis
  • sepsis is a condition of life-threatening organ dysfunction due to a dysregulated host response to infection

Reference:

• NICE (November 2021). Feverish illness in children Assessment and initial management in children younger than 5 years