Fever

Fever

Fevers are common in children. Fever by itself does not tell you whether your child is seriously sick. Even an ordinary cold can cause a high fever.

Key points to remember

Baby crying with thermometer under arm

If your baby with a fever is under 3 months old, you should always see a doctor.

  • a viral infection (such as a cold) is usually the cause of a fever in a child
  • if your child looks unwell and you are worried, take them to a doctor whether they have a fever or not
  • if your child has already seen a doctor but they are getting worse, go back to your doctor
  • if your baby with a fever is under 3 months old, you should always see a doctor

What is fever?

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

Fever by itself does not tell you whether your child is seriously sick.

If your child is miserable and seems unwell, and feels hot, you can use a thermometer to take their temperature if you want to. See Thermometers - how to use them. It is not really necessary to do this if your child seems well.

The number on the thermometer cannot tell you:

The number on the thermometer cannot tell you what is causing the fever or how sick your child is.

  • what is causing the fever
  • how sick your child is

What causes fever?

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

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.

Other causes of high body temperature include:

  • immunisation - this usually causes only mild fever
  • wrapping a baby in too many warm layers of clothing, or bedding

Will a fever harm my child?

Fever is a normal way for a child to fight an infection. Being hot may make your child feel unhappy or uncomfortable, but the high temperature is very unlikely to cause any long-term problems.

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

See Febrile seizures on this website.

When should I seek help?

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

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

If your child has already seen a doctor but they are getting worse, go back to your doctor.

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

When should I dial 111?

Dial 111 within New Zealand (use the appropriate emergency number in other countries) and ask for urgent medical help if your child:

  • has blue lips and tongue
  • has severe difficulty breathing
  • has any episodes of irregular or stopping breathing
  • has a worrying rash especially one that does not go away when you press on it (see a photo of a meningococcal rash)
  • is unconscious or you can't wake them up properly

When should I see a doctor urgently?

You should see a doctor urgently if your child with a fever:

  • is under 3 months old - young babies need a different and more cautious approach
  • looks unwell and you are 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, has 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)

When should I see a doctor?

You should see a doctor if your child with a fever:

  • is under 3 months old - young babies need a different and more cautious approach
  • has a sore throat or joint pains
  • is drinking less than half of their normal breastmilk or other fluid
  • is having fewer than 4 wet nappies in 24 hours
  • vomited half or more of their feed for the last 3 feeds
  • has frequent and watery poo (diarrhoea)
  • complains or cries when doing wee
  • is in pain
  • is getting sicker
  • is not improving after 2 days
  • has had a fever for more than 5 days

When is it OK to look after my child at home?

You can look after your child with a fever at home if they:

  • are drinking and feeding well
  • are still interacting with you
  • do not look sick

Is there anything I need to tell my doctor?

Tell your doctor if your child:

  • has been overseas in the last few weeks
  • has been around someone who is unwell

What about my young baby with a fever?

Young babies (less than 3 months old) need a different and more cautious approach:

  • if they have a fever, make sure to go to your doctor
  • if you are worried about them, take them to your doctor even if they do not have a fever
  • some babies may have an unstable temperature with an infection - they may be colder than normal - in a sick infant this is a worrying sign and is a reason to see a doctor urgently
  • babies get fevers for the same reasons as older children, but they are not as good at fighting off infections

You need to keep your baby warm but they can get too hot if you wrap them in too many layers when they are in a warm place. A good guide is to dress your baby in one more layer than you are comfortable wearing in the same environment.

Remember: Always take your baby to a doctor if they have a fever and are less than 3 months old.

How do I treat a fever?

Undress your child so that they are just wearing a single layer (maybe a singlet and pants). Make sure the room is not too hot or too cold. These are the best and most comfortable ways to bring your child's temperature down. It's best not to give your child a bath or shower to cool them. You could use a cool face cloth.

Your child may need extra rest or they may want to play - this is OK.

Encourage them to drink fluids and eat healthy small meals.

Medicines

If your child is happy, and they are not unwell, you do not need to do anything more. You do not need to treat the fever with a medicine.

Paracetamol
If your child is miserable because of the fever, you can give paracetamol to make them more comfortable. You must follow the dosage instructions on the bottle. It is dangerous to give more than the recommended dose.

You don't need to give paracetamol to your child before or after immunisation.

Other medicine
If your doctor gives your child ibuprofen, use it only if your child with a fever is miserable.

Don't give your child cold and flu medicines.

Never give your child aspirin as this may increase the risk of Reye syndrome, which is a rare and serious illness.

This page last reviewed 08 June 2018.
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