Fever advice

Fever in children is a common reason for seeing a doctor or attending a hospital. From a health professional’s perspective the most important aspect is to assess the child and find the cause. Treatment of the fever is secondary. This article explains fever and demystifies some of the misinformation surrounding fever

What Causes Fever?


Fever helps mobilise the immune system and impairs the function of viruses and bacteria. In most children – particularly those who are immunised – the fever is caused by a virus, but more serious bacterial infections need to be considered.

How do doctors assess a fever ?

For doctors, finding the cause of the fever is the most important part of the assessment.  Taking a history and examining the child will give an overall opinion of how unwell the child is.   Age,  hydration, level of activity, breathing rate, pulse rate, state of alertness are all factors that should be assessed. An unwell infant, who appears lethargic and has a temperature of 38 degrees is far more concerning than a well looking healthy child with a high temperature approaching 40 degrees.M

How long should a fever last ? 

For most viral infections the fever peaks around day 2-3 then apart from the occasional spike the fever will abate.  In some cases the fever can last for up to a week. If you child has ongoing fevers, and there is no obvious cause, a review assessement is recommended if there is still fever after 5-6 days. 

Measuring a fever

Fever is measured by either a digital under the arm thermometer, or an infrared ear or forehead device.   A fever is generally any temperature above 37.4 degrees celsius. Forehead adhesive plastic thermometers are not recommended.

Fever in an infant. 

  • Infants under 3 months have poorly developed immunity and are vulnerable to serious infections. In this age group any infant with a fever needs to be assessed.  If the cause of the fever is unclear on history and examination then investigations such as  urine and blood examination are required.  Infants can deteriorate quickly and are ‘hard to read’.  This should be done in a hospital with good paediatric support
  • Infants between 3 – 12 months with a temperature can be reviewed by a GP depending on how unwell he or she is.  If immunsations are up to date the most common causes are viruses, such as coughs, and colds. Tests will be unnecessary unless the infant appears unwell.   However if there is no obvious cause for the fever, further investigations may be needed. The most common cause of fever that is not due to a virus is a urine infection, particularly in infant girls. If the infant is unwell then hospital assessment is mandatory.

Fever in toddlers – 12 to 36 months

  • Between 12 – 36 months of age fully immuniseed toddlers with a fever will generally be due to viruses. However if after examination and history the cause of the fever is still unclear and the child appears unwell then further investigations are needed, such as urine and blood tests.

Fever in children

  • Older children will have a more mature immune system and in most instances the cause of the fever is obvious and can be managed accordingly.
  • If a fever lasts more than a few days it is worth being assessed, especially if the source is unclear.

Fever management

  • Dress your child comfortably. 
  • Give your child frequent small drinks of clear fluid (eg. water, diluted fruit juice or cordial). Do not worry if your child refuses to eat at this time. 
  • Paracetamol or nurofen can be given especially at night when the child fever can cause irritability and discomfort. 
  • Cool flannel to forehead will help with the discomfort but is not essential

Febrile Convulsions and other Fever Facts

  • A fever generally means 38 degrees or above. Viruses and bacteria do not like a higher temperature.
  • Cool baths to ‘get the fever down’  are not recommended and are not necessary.
  • If the child is otherwise well, and the source of the fever is known, (such as a cold or sore throat), the fever is of little consequence
  • Febrile convulsions  occur in only 3% of the population.  There is no evidence that controlling a fever with panadol, or sponging will prevent those that are susceptible from having a seizure. Many in the health profession will be unaware of this and will  contribute to a parent’s concerns about fever by concentrating on trying to lower the temperature.
  • There is no such thing as brain damage from a fever caused by an illness. Prior to  the 19th century this was a common held theory and people died during febrile illnesses.  In those days microbiology and science was only just starting to understand how infections worked. It was discovered the fever was a side effect of the infection not the cause of death or brain damage.


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