Fever in children
Fever in children

A fever is a high temperature. As a general rule, in children, a temperature of over 37.5°C (99.5°F) is a fever.

As a parent it can be very worrying if your child has a high temperature, however, it is very common and often clears up by itself without treatment.

A quick and easy way to find out if your child has a fever is to take their temperature using a thermometer.

What causes a high temperature?

Most fevers are caused by infections or other illnesses. The high body temperature makes it more difficult for the bacteria and viruses that cause infections to survive.

Common conditions that can cause fevers include:

Your baby’s or child’s temperature can also be raised during teething (when the teeth start to develop), following vaccinations or if they overheat due to too much bedding or clothing.

When to seek urgent medical advice

You should contact your GP or health visitor urgently if your child:

  • is under three months of age and has a temperature of 38°C (101°F)  or above
  • is between three and six months of age and has a temperature of 39°C  (102°F) or above

You should also see your GP if your child has other signs of being unwell, such as persistent vomiting, refusal to feed, floppiness or drowsiness.

If it isn’t possible to get in contact with your GP call your local out-of-hours service or NHS Direct on 0845 4647.

If your child seems to be otherwise well – for example, if they're playing and attentive – it's less likely they're seriously ill.

Treating a fever

If your child has a fever, it's important to keep them hydrated by giving them plenty of cool water to drink. Babies should be given plenty of liquids, such as breastmilk or formula. Even if your child isn't thirsty, try to get them to drink little and often to keep their fluid levels up.

To help reduce your child’s temperature you can also:

  • keep them cool if the environment is warm – for example, you can just cover them with a lightweight sheet (but they should be appropriately dressed for their surroundings)
  • keep their room cool - 18°C (65°F) is about right (open a window if you need to)

Sponging your child with cool water isn't recommended to reduce a fever.


Children's paracetamol or ibuprofen work as antipyretics, which help to reduce fever, as well as painkillers. You can't give them both at the same time, but if one doesn’t work you may want to try the other later.

Antipyretics aren't always necessary. If your child isn't distressed by the fever or underlying illness, there's no need to use antipyretics to reduce a fever.

When using antipyretics, always read the patient information leaflet that comes with the medication to find the correct dose and frequency for your child’s age.

More serious illnesses

Sometimes, a high temperature in children is associated with more serious signs and symptoms such as:

Possible serious bacterial illnesses include:

  • meningitis - infection of the meninges (the protective membranes that surround the brain and spinal cord)
  • septicaemia - infection of the blood
  • pneumonia - inflammation of the tissue of the lungs which is usually caused by an infection

It's important to remember that potentially serious causes of fever are relatively rare.

How do I take my child’s temperature?

If you’re concerned that your baby has a raised temperature, the best first step is to check their temperature with a thermometer. This will help you work out whether you need to call a doctor. If you speak to a doctor or nurse on the phone, it will help them make a decision about the type of medical attention your child needs.

Ideally, to get a fast and accurate reading of your child’s temperature, you need a digital thermometer. These are available from pharmacies and most large supermarkets.

Digital thermometers

To find out your child’s temperature, hold them comfortably on your knee and place the thermometer under their armpit (always use the thermometer under the armpit with children under five). Gently but firmly hold their arm against their body to keep the thermometer in place for the time stated in the manufacturer’s instructions (usually about 15 seconds). Some digital thermometers beep when they are ready. The display on the thermometer will then show you your child’s temperature.

Other types of thermometer

Other types of thermometer are available, but may not be as effective as a digital thermometer for taking a baby or small child’s temperature.

Ear (or tympanic) thermometers allow you to take a temperature reading from the ear. These thermometers are quick but expensive, and can give misleading readings, especially in babies, if they’re not correctly placed in the ear.

Strip-type thermometers are held on to the child’s forehead, and are not an accurate way of taking a temperature. They show the temperature of the skin, rather than the body.

Mercury-in-glass thermometers should not be used. They are no longer used in hospitals and not available to buy. They can break, releasing small shards of glass and highly poisonous mercury. If your child is exposed to mercury, get medical advice immediately.

How can I make sure the reading is accurate?

If you use a digital thermometer under your child’s armpit, and follow the manufacturer’s instructions carefully, you should get an accurate reading.

However, there are a few circumstances that could slightly alter the reading, for example if your child has been:

  • wrapped up tightly in a blanket
  • in a very warm room
  • very active
  • cuddling a hot water bottle
  • wearing a lot of clothes
  • having a bath

If this is the case, allow them to cool down for a few minutes (without allowing them to become cold or shivery), and take their temperature again to see if there has been any change.

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The information on this page has been adapted by NHS Wales from original content supplied by NHS Choices.
Last Updated: 03/02/2016 13:45:10