Fever in children

Fevers are also known as a high temperature. 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.

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On this page, you can find the following information:

What is fever?
What causes fever in children?
Will a fever harm my child?
When should I seek help for my unwell child?
Do I need to worry more about my young baby with a fever?
How do I treat a fever in my child?

Key points

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.
See below: Do I need to worry more about my young baby with a fever?

What is fever?

Your child's normal body temperature is around 37ºC.

Mild fever: Your child has a mild fever if their temperature is higher than 38ºC.
High fever: A high fever usually means more than 39ºC.

Read more about thermometers and how to use them.

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. It is not really necessary to do this if your child seems well. The number on the thermometer cannot tell you what is causing the fever or how sick your child is.

Image credit: Canva

What causes fever in children?

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. Read more about febrile seizures.

When should I seek help for my unwell child?

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 phone 111?

Phone 111 within New Zealand 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 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).

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:
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 about my child with a fever?

Tell your doctor if your tamariki:

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

Do I need to worry more 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 baby 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 in my child?

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. Read more about paracetamol in children.

You don't need to give babies and children paracetamol before or after immunisation. There is some evidence that paracetamol may reduce the effectiveness of childhood immunisations.

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.

Learn more

Fever KidsHealth, NZ
Fever in children Ministry of Health, NZ
Fever in children – does my child need medicine? Choosing Wisely, NZ

	Credits
	Content courtesy of KidsHealth NZ which has been created by a partnership between the Paediatric Society of New Zealand (PSNZ) and the Starship Foundation, supported and funded by the Ministry of Health.