Fever in children

Written by Dr Stuart Crisp, paediatric specialist registrar and Dr Per Grinsted, specialist

Temperature control in the body
The 'core temperature' means the temperature of the deep tissues of the body and in normal circumstances this is kept at a very even level by a range of automatic adjustments.

When we are too hot we increase the amount of blood flowing through the skin by opening up the tiny capillary blood vessels. This radiates away excess heat and sweating can further enhance this.

When we are too cold we shut down skin blood vessels and conserve heat within the internal organs. If necessary we can generate more heat by shivering.

Fever is part of the body's defence mechanism against viruses or bacteria. The body tries to create extra heat so that the foreign organism cannot survive. Having a temperature helps you fight illness.

Actions to reduce a fever can help make someone feel more comfortable but it is not possible, or desirable, to aim to normalise the temperature while someone is fighting off an infection.

The part of the human brain that controls body temperature is not fully developed in children. This means that a child's temperature may rise and fall very quickly and the child is sensitive to the temperature of his or her surroundings.

One of the simplest and most effective ways to help a child with a fever feel more comfortable is to take off some of the child's clothes so heat can escape from their body more easily.

What is the normal temperature for a child?
If you take the temperature in your child's mouth or from the ear, the normal temperature is 36-36.8ºC (97.7-99.1ºF).

Thermometers
Traditional mercury thermometers are being phased out although many are still around. Mercury is a highly toxic substance if taken into the body, which can be done through skin contact, breathing in the vapour or swallowing it.

All these risks can apply to the fragile glass thermometer if it is broken, for example by a child biting it.

If you have a mercury thermometer, check with your local council how to dispose of it safely.

Modern probe-type digital thermometers are quicker to use, more reliable and are much safer if bitten.

Taking a child's temperature
A body temperature reading can be taken from the mouth, armpit, ear, skin surface or the rectum.

Temperature tips You can take a reading:

from your child's mouth

under the arm

in the ear

using a forehead strip.

Ear temperature
If you are willing to pay for an ear thermometer, this is a very quick method and will give a read-out in seconds. Ear thermometers rely on measuring infrared (heat) radiation from the eardrum.

Other types of thermometer (such as the probe type) are not suitable for taking ear readings and must never be placed within the ear canal.

Some ear thermometers are adjustable so they can be made suitable for adults or children.

To get a reliable temperature measurement, the thermometer must be used exactly as directed.

When you buy the thermometer, ask the salesperson how to use it, and read the instructions carefully before you start.

Especially with small children, ear thermometers require a steady hand to find the right spot.

The ear canal has a natural curve, so to ensure that the thermometer is pointing towards the eardrum it may be necessary to pull the top part of your child's ear gently upwards during the reading.

If your child has been lying with their head on a warm pillow, or has just come inside out of the cold, you will need to wait 10 to 15 minutes before the ear can provide an accurate measurement of body temperature.

Under the armpit
This method is not good for small children, since they will not stay still for long enough.

With children old enough to co-operate and keep still you need to keep the thermometer under their armpit for at least 5 minutes.

From the mouth
This method is not suitable for a young child, because they may bite the thermometer and break it.

The thermometer is placed in the mouth, under the tongue.

It will take two to three minutes to measure the temperature accurately.

If your child has just eaten anything hot or cold, you will need to wait 10 minutes before an accurate temperature can be taken.

What can I do if my child has a temperature?

Liquids A child with a high temperature needs more liquid than usual, because the fever will make them sweat a lot.

Make sure your child drinks plenty of liquids - a teaspoonful every few minutes, if necessary. Provided they drink plenty of liquids, it won't matter too much if they eat very little for a couple of days.

Tackling fever

Make sure your child drinks plenty of fluids.

Let them rest.

Keep them cool.

Get advice on medicines.

Give them lots of 'TLC' (tender loving care).

Rest
A child with a high temperature also needs rest and sleep. They do not have to be in bed all day if they feel like playing, but they must have the opportunity to lie down.

Body temperature
You do not sweat out a fever. If your child shivers while their temperature is rising, it's okay to cover them with a duvet or a blanket. But as soon as your child's temperature has stabilised and he or she starts sweating, they need to cool down.

Your child only needs to wear underwear or a nappy, which will help the heat escape from the body. Make sure their room is ventilated and cool, but not draughty.

Medicines
If you want to use medication to get the temperature down, ask your doctor or pharmacist. They will be able to tell you what to use and how much. The dosage will depend on both the age and weight of your child.

Paracetamol suspension (eg Calpol) is the usual choice and ibuprofen (eg Nurofen for children) is an alternative. Aspirin should not be given to children under 16 years of age.

Attention
Sick children are often tired and bad-tempered. They sleep a lot and when they are awake; they want their parents around all the time. They might whine and act younger than their age.

It is okay to give in and spoil a child a little when they are sick. Read to them, play with them and spend time with them. This is not the time to teach a child good manners.

A child usually recovers quickly and will go back to their old self again.

When is a fever critical?
Look at your child and use common sense. Do they look exhausted or ill? Are they behaving differently? If the answer is yes, call the doctor. You should also call your doctor if:

you have a young child, less than three months old, who runs a high fever.

your child cries and cries, without you being able to comfort them, and doesn't wake up easily.

your child has a temperature over 38ºC (101.3ºF) for more than three days.

your child has just had an operation.

your child doesn't seem to be getting better.

If your child experiences any of the following symptoms with a fever, call your doctor.

Stiff neck.

Affected by bright light.

Hallucinations.

Red rash or blue/purple dots or patches.

Trouble breathing.

Cramps.

Continued vomiting or diarrhoea.

Continued tonsillitis.

Pain when urinating, or urinating more than usual.

Other illnesses.

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