A fever is a temperature above 38°C. It is usually a sign of illness, but is not an illness itself. You should go to the hospital emergency department immediately if you have a baby under 3 months old with a fever.
What is a fever?
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. The temperature of a baby with a fever may rise above 38°C slowly over a few days, or it might rise very quickly.
While a fever may be a sign of illness, it is rarely harmful in itself because it is the body’s natural response when fighting off an infection. A high fever doesn’t necessarily mean that your baby has a serious illness.
What causes a fever?
A fever is the body’s response to an infection. It could be a viral infection, such as a cold or a gastro bug, or it could be a bacterial infection, such as some ear and throat infections or pneumonia or meningitis.
Fever can also be a side effect of vaccinations.
Research suggests that teething probably does not cause fevers.
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 digital thermometers:
Digital probe thermometers can be used in your child's mouth (orally) or under their armpit (axillary). This type of thermometer is very common and a temperature taken orally will be more accurate.
Digital ear thermometers are quick and easy to use, but will give you less accurate readings.
Digital temporal artery thermometers use infrared scanning to your child's forehead. These thermometers are both easy to use and 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 a 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 you 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
- displays 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 healthdirect on 1800 022 222 at any time to speak to a registered nurse (known as NURSE-ON-CALL in Victoria). You may also wish to use the Symptom Checker.
Treating a fever at home
If your baby is older than 3 months and seems well, you can treat a fever at home.
- For babies that are breast or formula fed, they should have smaller, but more frequent feeds.
- Babies older than 6 months should have frequent small drinks of clear fluid, such as water.
- Don’t worry if they don’t feel like eating (but do worry if they’re not drinking).
- 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 and do not give for more than 2 days without seeing your doctor. Babies older than 3 months can also have ibuprofen.
Doctors now recommend that you don’t sponge babies or put fans on them to reduce their fever. The Australian College of Nursing also advises against routinely giving medicines solely to reduce fever to children who are showing no signs of distress. Talk to your doctor or visit the Choosing Wisely Australia website for more information.
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Last reviewed: June 2020