Fever: how to treat for under fives

What is fever?

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

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's not really necessary to do this if your child seems well.

The number on the thermometer cannot tell you:

  • 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:

  • immunisations - these usually cause 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 convulsions when they have fevers. These look very worrying, but even these febrile convulsions are very unlikely to cause long-term problems.

See Febrile convulsions 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 your child has already seen a doctor but they are getting worse, you should take them back for another check.

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

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

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. See 'What is special about young babies?' below

❕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 if your child with a fever:

❕is under 3 months old - young babies need a different and more cautious approach. See ‘What is special about young babies?’ below

❕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

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

Tell your doctor if your child:

🌿 has been overseas in the last few weeks

🌿 has been around someone who is unwell

What is special about young babies?

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

❕if they have a fever, they should always be checked by a doctor

❕if you are worried about them, they should be checked by a 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 a reason to see a doctor urgently

❕babies get fevers for the same reasons as older children, but they're not as good at fighting off infections

Babies need to be kept warm, but they can get too hot if wrapped in too many layers when they're 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.

How do I treat a fever?

Undress your child so that they are just wearing a single layer (for example, a singlet and pants). Make sure the room is not too hot or too cold. Put cool cloths on your child’s face, arms and neck to help them cool down. These are the best and most comfortable ways to bring your child’s temperature down. Don’t use any rapid cooling methods that make your child shiver. (The muscle movement in shivering will actually raise your child’s temperature and can make their fever worse) Putting your child in the bath or shower to cool them is not recommended. 

Your child is their own best guide to the level of activity that you allow. They may need extra rest or they may want to play.

Encourage them to drink fluids and eat healthy small meals.


❕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

❕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

❕paracetamol may reduce the effectiveness of childhood vaccinations to stimulate lasting immunity (infection-fighting ability). For this reason, it's not recommended for routine use before or after vaccination

❕if you have been given ibuprofen for your child, you shouldn’t use it as well as paracetamol. Use one or the other, and only if your child with a fever is miserable

❕cold and flu medicines are not recommended for babies and children

❕never give your child or young person aspirin as this may increase the risk of Reye syndrome, which is a rare and serious illness

Related articles: Baby's temperature

                        When to call your doctor

Source: & Ministry of Health


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