Fever in children is an increase in body temperature and is usually a protective response to infection. The raised body temperature increases the activity of the body’s defence mechanisms – which may cause some discomfort to the child.

Fever occurs when the body’s internal ‘thermostat’ raises the body temperature above the normal level. This ‘thermostat’ is situated in the part of the brain called the hypothalamus. The hypothalamus keeps the body temperature at about 37?C

Children’s body temperatures change very little during the day, being slightly lower in the mornings and a bit higher towards evening. Temperature can also change slightly when children run around and play or exercise.

Sometimes the hypothalamus ‘resets’ the body to a higher temperature in response to an infection. It is thought that this increased body heat helps to fight the germs that cause infection.

Some children, usually those under three years, may have a seizure (fit) if their temperature goes above 39.5? to 40?C. This is uncommon and should not be regarded as a reason to treat all fevers in children.

Fever by itself is not an illness but a sign of infection, unless it is due to some other cause.

Causes of fever

Infection:  Most fevers are the result of infection by bacteria, viruses or some other organism. The fever helps the body to fight the infection by stimulating its natural defence mechanisms.

Overdressing: Infants may get a fever if they are overdressed or bundled up, especially in a hot environment because they cannot regulate their body temperature as well as older children. However, because fever in a new born baby can indicate a serious infection, even those infants who are probably overdressed must be seen by a doctor if they have a fever.

Immunisations (Vaccinations): Babies and children often have a slightly raised temperature for a day or two after having had a routine vaccination.

Teething: Although teething can cause a slight rise in temperature in some infants, it is not the cause if a baby’s temperature is higher than 37.5?C.

When is a fever a sign of something serious?

Doctors usually recommend that temperature be regarded as part of the child’s overall condition. A fever does not require treatment unless there is a specific need to do so.

Children who have a temperature lower than 38?C usually do not require any medication unless they are uncomfortable. This does not apply to infants of 3 months or younger who have a temperature of 38?C or higher, as this can be a sign of serious infection.

Children between 3 months and 3 years with a fever of 39?C or higher should be seen be a doctor. In older children, behaviour and activity levels should be taken into account. If parents are concerned about a child with a fever, it is always safer to take the child to see a doctor.

An illness is usually not serious if the child:

    • Is interested in playing

    • Is eating and drinking normally

    • Is alert and smiles

    • Has normal skin colour

    • Is not vomiting

How to take a child’s temperature

The normal temperature taken in the child’s mouth or from the ear is 36.?C to 36.8?C.


The old fashioned glass thermometers containing mercury are being phased out, although many are still around. Mercury is toxic if swallowed, and this may well happen if a child accidentally bites and breaks a glass mercury thermometer.

Modern digital thermometers are simple to use and are more reliable and safer for children.

Your child’s temperature can be taken, using the following methods


Although a rectal temperature reading is the most accurate and is often taken in hospital for infants, it is not necessary to be so precise when taking the temperature reading at home. Taking temperatures rectally at home is not recommended.

Under the arm

If you take a temperature measurement from your child’s armpit, this reading will be about 0.5?C lower than the oral temperature.  This method may be difficult to use in some small children since they may not keep still for long enough. The thermometer must stay in the armpit for at least 3 minutes.

Thermometer strips

Placed on a child’s forehead, these will only give a rough guide and are not regarded as being accurate. It is not always necessary to get an exact temperature reading and if it is above 38?C, it is an indication that a fever is present.

In the ear

An ear thermometer is quick and easy to use and gives a read-out in seconds. Ear thermometers measure the temperature of the child’s ear drum. To get a reliable temperature reading, the thermometer must be used exactly as directed. Carefully read the instructions before you start. Ear thermometers require a steady hand and you must ensure that the thermometer ear piece is pointing towards your child’s ear drum. This method is useful for all children.

In the mouth

This method is not suitable for very young children who may refuse to keep the thermometer in their mouths or try to bite it. Place the digital thermometer under the child’s tongue and keep it there for at least 2 minutes or until the device gives a signal that the reading has been completed.

What to if your child has a fever


A child with a high fever needs more liquid than usual because the fever will cause increased sweating and fluid loss. Make sure that your child drinks plenty of liquid. Provided they drink enough it will not matter if they eat very little for a day or two.

Dealing with the fever

Besides ensuring that your child drinks plenty of fluids, it is important that they rest as much as possible. They need not stay in bed if they want to play but should not be allowed to run around or be too active. Keep your child cool and get advice on medicine. Remember that a mild fever does not need to be treated, but the underlying cause may sometimes require treatment.

Body temperature

If your child shivers due to raised temperature it is fine to cover them with a blanket or light duvet, but as soon as their temperature has stabilised or they start to sweat, they need to cool down. Your child should only wear underwear or a diaper, as this will help heat to escape from the body. Make sure that the room is well ventilated and cool but not draughty.


If you need to use medication to reduce your child’s temperature it is best to ask your doctor or pharmacist. They will advise about the safest medicines to use, and especially about the correct dose. The dose will depend on the age and weight of your child. Paracetamol liquid is the usual choice, but Ibuprofen liquid can also be used. Although both are safe to use in children it is essential to follow dosage instructions carefully.

Aspirin should not be given to children under 16 years of age for a fever, because it increases the risk of a serious illness called Reye’s syndrome which can be fatal.

Further information

Sick children are often miserable and grumpy. They may sleep a lot and when they are awake they may want their parents around all the time. It is fine to spoil your child a little when they are sick. Read to them, play with them and spend time with them. Children usually recover and return to normal quite quickly.

When is a fever serious?

Look at your child and use common sense. Do they appear ill and unusually tired or lethargic? Are they behaving differently? If you are concerned contact your doctor. You should also see the doctor if:

    • Your baby of less than 3 months has a fever.

    • Your child keeps crying and you are unable to comfort them.

    • Your child does not wake easily or is drowsy.

    • Your child vomits repeatedly.

    • Your child has a fever over 38oC lasting more than 3 days.

    • Your child has had a recent operation.

    • Your child does not seem to be getting better.

Urgent medical attention

If your child experiences the following Symptoms they must see a doctor urgently:

    • Stiff neck

    • Affected by bright light

    • Hallucinations

    • Red or purple dots or spots or rash on skin

    • Difficulty in breathing

    • Pains in Joints

    • Continual Vomiting

    • Any Fit or Seizure

    • Pain on passing urine or frequent passing of urine

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