How to check a baby's temperature

Babies can't let you know when they're feeling under the weather, and this can be upsetting for both them and you! If you suspect that your little one is unwell, it's important to take a temperature reading to understand how they're feeling and decide the best course of action.

We've written this guide to help you learn how, when, and how often to take a baby's temperature, and to let you know when to seek medical attention.

How to use a thermometer to check a baby's temperature

Digital thermometers provide fast and accurate readings and can be used to take a reading from a baby's forehead, armpit, mouth, or in their ear.

It's a good idea to find out what your little one's 'baseline' temperature is when they're feeling well. For consistency, you should always take their temperature from the same location - oral, armpit, ear, or forehead.

Although it's possible to use a digital probe thermometer to take a baby's rectal temperature, this can potentially damage the lining of their rectum, so isn't recommended.

Old-fashioned glass thermometers contain mercury and can break and release small splinters of glass and highly poisonous mercury. They're no longer used in medical settings, can't be bought in shops, and should never be used to take a baby's temperature.

It's best to carefully follow the instructions for your specific thermometer but to help you out, we've created a basic step-by-step guide to each method:

Forehead (temporal artery) reading

From birth, you can take a forehead temperature reading from your baby using a no-touch infrared thermometer.

1. Check that your baby's forehead is dry.
2. Hold the scanner one to three centimetres away from the centre of their forehead.
3. Press the start button.
4. Their temperature will then be shown on the display.

Oral reading

If you're using an oral probe thermometer, don't take your child's temperature straight after they've had hot or cold food or drinks.

1. If possible, your baby's mouth should stay closed for up to five minutes before you take a reading.
2. Gently place the probe well under their tongue.
3. Ask them to hold it gently with their lips and not to bite it.
4. Keep the probe in their mouth and wait for the thermometer to beep.
5. Their temperate reading will show on the digital display.

Underarm (axillary) reading

From birth, a digital thermometer with a soft and flexible probe can be comfortably positioned under a baby's armpit to take their temperature.

1. Ensure your baby's armpit is dry.
2. Turn the thermometer on.
3. Place the thermometer's probe under their armpit.
4. Press their arm tightly next to their body.
5. Ensure the sensor is covered under their armpit.
6. The unit will beep once the temperature reading is ready, and it will be shown on the digital display.

In-ear (tympanic membrane) reading

If your little one is aged three months and up, you can take an in-ear temperature reading using a specially designed digital in-ear thermometer. This method only takes a few seconds, so is handy if your baby is fussy and difficult to keep still.

1. Ensure your baby's ear canal is clean.
2. Securely put a new disposable hygiene cover onto the end of the thermometer.
3. Try to keep your baby's head still.
4. Gently pull their ear back to straighten their ear canal.
5. Position the covered tip snugly in your baby's ear opening. Remember not to use force and to never let the tip of the thermometer touch your baby's eardrum.
6. Turn the thermometer on.
7. To take a reading, follow the instructions for your thermometer.
8. Take the thermometer out of your baby's ear.
9. The digital display will show their temperature reading.
10. Take off the hygiene cover and dispose of it.

When using a digital thermometer to take your baby's temperature, be sure to always follow the manufacturer's instructions carefully so that you get an accurate reading.

If your baby has been wrapped up tightly in a blanket, is in a very warm room, wearing lots of layers or having a bath, you may find that their temperature is elevated. Therefore, the reading you get will be slightly inaccurate. It's a good idea to let them cool down for a minute or two, then take their temperature again to see if there's any change.

How to check a baby's temperature without a thermometer

Using a digital thermometer is the best and most accurate way to take your little one's temperature. But if you don't have access to one, there are other fever symptoms you can look out for.

If you can answer 'yes' to any of the below points, your baby may have a fever:

• Do they feel hot to the touch or very warm on their forehead, stomach, or neck when you touch them with the back of your hand?
• Do they seem fussier, weaker, or more tired than usual?
• Are they avoiding feeds?
• Are their cheeks flushed and more red than usual?
• Are their eyes sore?
• Are they sweating or shivering?

When to see a doctor about a fever in a baby

It can sometimes be hard for parents to distinguish normal fussiness or mild illnesses from serious problems. While all little ones get poorly from time to time, there are some occasions when they'll need to visit your healthcare provider for treatment.

If you're worried about your baby's symptoms, don't hesitate to call your doctor. Let's run through when to get medical support and advice if you're concerned about your baby's temperature.

You should contact your healthcare provider if your baby...

• is three months old or younger and shows any sign of having a fever.
• is aged between three and six months, has a temperature up to 38°C and seems sick.
• is aged between six and 24 months and has a temperature that's above 38°C and lasts longer than one day, without any other signs or symptoms.
• has a high temperature and other symptoms like a cold, cough, or diarrhoea.

Other symptoms that require medical attention include your baby...

• refusing several feeds in a row or having a reduced appetite.
• being unusually sleepy or hard to wake up.
• crying more than usual.
• vomiting a lot after feeds.
• crying with fewer tears, having significantly fewer wet nappies, or having a dry mouth. These can be signs of dehydration along with the soft spot on the top of their head appearing sunken.
• being constipated.
• having a cold and congestion that interferes with their breathing.
• experiencing ear pain or a cough that lasts for more than one week.
• developing an unexplained rash.
• having swollen, red or irritated eyes.