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HealthInfo Waitaha Canterbury

Overview of fever (high temperature) in children


You should always see a doctor if a pēpi (baby) under 3 months old has a fever.

Phone 111 for urgent medical help if your tamaiti (child):

  • has blue lips and tongue
  • has severe difficulty speaking
  • has irregular breathing or stops breathing
  • has a worrying rash, especially one that doesn't go
    away when you press it
  • is unconscious or you cannot wake them up properly.

Child with a fever sleeping Fevers are common in tamariki (children). A fever by itself doesn't tell you if they're seriously sick. Even an ordinary cold can cause a high fever.

Your child's normal body temperature is around 37°C. Your tamaiti child has a mild fever if their temperature is higher than 38°C. A high fever usually means more than 39°C.

If your tamaiti is miserable, seems unwell and feels hot, you can use a thermometer to take their temperature. You do not need to do this if they seem well.

The number on the thermometer cannot tell you:

The most common cause of a fever in a tamaiti is a viral infection. A bacterial infection is a less common but more serious cause.

Other causes of high body temperature include:

Fever is a normal way for a tamaiti to fight an infection. The body's natural reaction to infection with a virus or bacteria is to raise the temperature inside the body. This helps to kill the infection.

Being hot may make your tamaiti feel unhappy or uncomfortable, but the high temperature is very unlikely to cause any long-term problems.

Some tamariki children have convulsions (called febrile convulsions) when they have fevers. These look very worrying, but even these febrile seizures are very unlikely to cause long-term problems.

Getting help for your child with a fever

If you're worried about your tamaiti, whether or not there is a fever, you should take them to see a doctor.

If they have already seen a doctor but they're getting worse, go back to your doctor.

Tell your doctor if your tamaiti has been overseas in the last few weeks or has been around someone who is unwell.

See a doctor urgently if the tamaiti with a fever:

  • is under 3 months old
  • looks unwell and you're concerned
  • is very pale or feels cold to touch
  • is floppy, sleepy or drowsy
  • is becoming less responsive
  • has an unusual high-pitched cry
  • has trouble breathing, noisy breathing or is breathing fast
  • complains of a stiff neck or light hurting their eyes
  • has a severe headache
  • refuses to drink, even small sips
  • is not doing wee
  • vomits a lot and cannot keep sips of replacement drinks down
  • vomits green fluid (bile)
  • vomits blood – this may be red or brown or look like coffee grounds if it is not fresh
  • is in severe pain
  • is not interested in surroundings (lethargic).

See a doctor if the tamaiti with a fever:

  • has a sore throat or joint pains
  • is drinking less than half their normal breast milk or other fluid
  • is having fewer than four wet nappies in 24 hours
  • has vomited half or more of their feed for the last three feeds
  • has frequent and watery poo (diarrhoea)
  • complains or cries when doing wee
  • is in pain
  • is getting sicker
  • is not improving after two days
  • has had a fever for more than five days.

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On the next page: Helping your child with fever (high temperature)

Content shared between HealthInfo Canterbury, KidsHealth and Health Navigator NZ as part of a National Health Content Hub collaborative. Last reviewed November 2021.

Page reference: 734318

Review key: HIFEC-49206