Introduction

A fever is a high temperature. As a general rule, in children, a temperature of over 37.5°C 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 on its own.

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. A fever helps the body to fight infections by stimulating the immune system (the body’s natural defence against infection and illness).

By increasing the body’s temperature, a fever makes it more difficult for the bacteria and viruses that cause infections to survive. Common conditions that can cause fevers include:

• flu
• ear infections
• roseola (a virus that causes a temperature and rash)
• tonsillitis 
• kidney or urinary infections
• common childhood illnesses, such as measles, mumps, chickenpox and whooping cough

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 or above
• is between three and six months of age and has a temperature of 39°C or above
• is over six months and shows other signs of being unwell - for example, they are floppy and drowsy or you are concerned about them

If it isn’t possible to get in contact with your GP call your local out-of-hours service or NHS Direct Wales on 0845 46 47.

If your child seems to be well, other than having a high temperature - for example, if they are playing and attentive it is less likely that they are seriously ill. 

Treating a fever

If your child has a fever, it’s important to keep them well hydrated by giving them plenty of cool water to drink. 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 - by undressing them to their underwear (you can cover them with a cool, lightweight sheet)
• keep their room cool - 18°C (65°F) is about right (open a window if you need to)
• give them paracetamol or ibuprofen - you can’t give them both at the same time, but if one doesn’t work you may want to try the other later (always read the patient information leaflet to find out the correct dose and frequency for your child’s age)

More serious illnesses

A high temperature in children is sometimes associated with more serious signs and symptoms such as:

• breathlessness
• vomiting
• rash
• fits or seizures 

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
• urinary tract infection 
• 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.