Fever in children

Also known as high temperature

Fever is when your body temperature is raised above the normal 37 degrees Celsius. A fever helps the body’s immune system to fight infection and by itself does not mean your child is seriously sick. However, you need to check for other signs of illness in case they need to see a doctor.

Key points

  1. Fever is usually caused by your body fighting a viral or bacterial infection. 
  2. A baby under 3 months with a temperature above 38ºC needs to be checked by a doctor.
  3. Older babies and children with a temperature above 40ºC should also be seen by a doctor.
  4. If your child has a fever and any of these warning signs, see your doctor urgently: rash, unusual sleepiness or floppiness, pain, irritability or persistent crying, inability to swallow, breathing difficulty, vomiting or loss of appetite.
  5. If your child looks unwell and you are worried, take them to a doctor whether they have a fever or not.
  6. You can treat most fevers at home with rest, fluids and generally keeping your child comfortable. Painkillers, such as paracetamol or ibuprofen, are not needed unless your child is distressed.

What are the signs of fever?

The normal body temperature is 37ºC. A fever is when body temperature is raised above this because of fighting off a virus or bacterial infection. The best way to find out whether your child has a fever is to take their temperature using a thermometer.

  • Mild fever (37.5–38.9°C) – your child might have flushed cheeks, feel a little lethargic and be warm to touch. They will generally be able to do their normal daily activities.
  • High fever (39–39.9°C) your child will feel hot to touch. They may not feel well enough to do their usual activities and may have aches and pains.
  • Very high fever (40°C or higher) – your child will usually want to stay in bed or be inactive; they won’t feel well enough to do their normal activities. They will feel hot to touch and may have lost their appetite. 

When to see a doctor

  • A baby under 3 months with a temperature above 38ºC needs to be checked by a doctor.
  • Older babies and children with a temperature above 40ºC should also be seen by a doctor.
  • It‘s also important to look at other symptoms and how unwell your child seems. Some mild diseases produce very high fevers and severe illnesses can produce mild fever.
When to seek urgent medical help

Signs of meningitis

Take your child to the doctor or emergency department quickly if they have the following symptoms along with a fever:

  • confusion
  • vomiting
  • a stiff neck (they’re unable to put their chin on their chest or have pain when moving their neck forward)
  • a skin rash (purple or red pinpricks).

These symptoms could be signs that your child has a serious illness like meningitis.

Other serious symptoms  

You must also seek urgent medical help if your child:

  • has a very high fever (over 40ºC)
  • is still feverish after 3 days of home treatment, or seem to be getting sicker
  • is shivering or shaking uncontrollably or have chattering teeth
  • has a severe headache that does not get better after taking painkillers
  • is breathing differently or having trouble breathing
  • is getting confused, unusually drowsy or you can’t wake them up properly
  • seems floppy or complains of leg pain
  • becomes dehydrated
  • has a fever that goes away for more than 24 hours and then returns.

Call Healthline 0800 611 116 if you are unsure what you should do.

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What causes fever in children? 

Fever is the body’s natural response to an infection somewhere in the body. Some types of infections that can lead to fever include:

Immunisation can also sometimes cause mild fever. However, it is not recommended you give children paracetamol routinely before or after a vaccination as it may make the vaccination less effective.

Wrapping a baby in too many warm layers of clothing, or bedding can also cause a fever. 

How do I look after a child with a fever?

If your child has a fever but is content, eating, drinking and playing, you do not need to do anything. Remember the fever is helping your child fight infection.

If your child is not comfortable, you can do the following:

  • encourage them to rest 
  • encourage them to drink lots of fluids, especially water – little and often is best
  • if they are hungry offer small healthy meals
  • make sure their room temperature is comfortable (not too hot or too cold)
  • use a cool cloth to wash their face, hands and neck.
  • don’t use any rapid cooling methods that make your child shiver – the muscle movement in shivering will raise your child’s temperature and can make their fever worse
  • keep your child in lightweight clothing and bedding, such as a singlet and pants covered by a sheet
  • change the bed linen and clothing regularly
  • do not use hot water bottles or electric blankets
  • check your child during the night
  • take them to the doctor if your child doesn’t seem to improve or you’re at all worried (see when to see a doctor).

Should I give my child painkillers for fever?

People often want to give their child medicine, such as paracetamol or ibuprofen, to bring down the fever. This is not necessary unless your child is distressed.

A fever is the body’s normal response to an infection, and fever can help slow the growth and spread of bacteria. So fever is a sign that your child’s immune system is doing its job – there is no need to try and bring down the fever.

If your child is in pain or is distressed, then painkillers can help them feel better. So if your child has a fever but is playing and happy, there is no need to give them paracetamol or ibuprofen. If your child has a fever and is miserable, paracetamol or ibuprofen can help.

  • Paracetamol: can be used for children older than 1 month to make them more comfortable. The dose of paracetamol is based on your child’s weight and not their age. Read more about how to give paracetamol to babies and children.
  • Ibuprofen: can be used for children older than 3 months but only if your child has a fever and is miserable. Read more about ibuprofen for children.
  • Paracetamol and ibuprofen: should not be given at the same time.

Other medicines

  • Cold and flu medicines: not recommended for babies and children.
  • Aspirin: never give your child or young person aspirin as this may increase the risk of Reye syndrome, which is a rare and serious illness.
  • Antibiotics: only work to kill bacteria. Most children with fever do not have a bacterial infection, so antibiotics will not help them.

Learn more

Fever KidsHealth, NZ, 2015

References

  1. Fever in adults  Ministry of Health, NZ, 2017
  2. Treating fever in children Choosing Wisely, NZ, 2018
  3. Fever and night sweats Patient Info, UK, 2015
Credits: Health Navigator Editorial Team.