You should go to the nearest hospital emergency department immediately if you have a baby under 3 months old with a fever above 38°C.
What is a fever?
A fever is a temperature above 38°Celsius (38°C). It is usually a sign of illness.
Most babies have an average body temperature of about 36.5°C to 38°C. A fever is when your baby’s body temperature rises above 38°C.
While a fever may be a sign of illness, it is not usually harmful.
What are the signs and symptoms of a fever?
Your baby or child may have a fever if they are:
- hot to touch
- crying and irritable
- more sleepy than usual
- not drinking or feeding as usual
Sometimes children can have seizures when their temperature rises suddenly – these are called febrile convulsions or seizures.
What causes a fever?
A fever is the body’s response to an infection. An infection with a virus is the most common cause of fever in children. Infections with bacteria can also cause fevers.
Fever can also be a side effect of vaccinations.
Teething does not cause a fever.
How to take your baby’s temperature
Using a thermometer is the best way to check your baby’s temperature.
There are several different types of thermometers.
Digital probe thermometers can be used in your child's mouth (orally) or under their armpit (axillary). In babies younger than 3 months old, it’s best to use this type of thermometer under their arm.
Digital ear thermometers are quick and easy to use, but may give you less accurate readings if not used properly. These thermometers are recommended for children older than 3 months.
Digital temporal artery thermometers use infrared scanning of your child's forehead. These thermometers are easy to use but not always accurate.
Mercury thermometers are no longer recommended as they can break and poison your child. Fever strips and digital pacifier thermometers are also not recommended as they are not very accurate.
Your doctor, nurse or pharmacist can show you how to use your thermometer properly.
If your child’s forehead or skin feels very hot, it’s a good idea to use a thermometer to take their temperature accurately.
When to seek medical help
If your baby is under 3 months old and has a fever, you should take them to the hospital emergency department immediately, even if they are not showing any other signs of being sick.
If your baby is 3 to 12 months old, a fever might be a sign of illness, so see a doctor for medical advice.
If your baby is over 12 months old, see a doctor if they have a fever and:
- have trouble breathing
- become drowsy
- don’t want to drink and aren’t weeing enough
- vomit repeatedly or have frequent episodes of diarrhoea
- display signs of a stiff neck, persistent headache or light hurting their eyes
- don’t improve in 48 hours
- are in pain
If you’re worried or not sure what to do, phone Pregnancy Birth and Baby on 1800 882 436 at any time to speak to a maternal child health nurse.
Treating a fever at home
If your baby is older than 3 months and seems well, you can treat a fever at home.
You may want to use the Symptom Checker.
CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.
Feeding and fluids
For breastfed babies younger than 6 months, offer extra breast feeds.
For formula-fed babies younger than 6 months, offer the usual amount of formula.
For babies older than 6 months, continue breast feeding or bottle-feeding. You should also offer frequent, small drinks of water or oral rehydration solutions. You can buy oral rehydration solutions from the pharmacy or supermarket.
Don’t worry if your child doesn’t feel like eating (but do worry if they’re not drinking).
Dress your baby so that they are not too hot or cold. For children who are shivering, you can add a layer of clothing or a blanket until they stop shivering.
You can try cooling your baby down by wiping your baby’s forehead with a sponge or face washer soaked in slightly warm water.
Cold baths and showers are not recommended for babies and children with a fever.
If your baby has a fever and they are miserable, you can give paracetamol for comfort. Make sure to follow the correct dose on the package.
Babies older than 3 months can also have ibuprofen for fever.
Speak to a maternal child health nurse
Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.
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Last reviewed: October 2022