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

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

A quick and easy way to find out whether 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:

• upper respiratory tract infections (RTIs)
• flu
• ear infections
• roseola (a virus that causes a temperature and rash)
• tonsillitis
• kidney or urinary tract infections (UTIs)
• common childhood illnesses, such as chickenpox and whooping cough

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

When to seek urgent medical advice

Contact your GP or health visitor urgently if your child:

• is under three months old and has a temperature of 38C (101F) or above
• is between three and six months old and has a temperature of 39C (102F) 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 contact your GP, call your local out-of-hours service or NHS 111.

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, 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.

Antipyretics

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.

Read more about treating a high temperature in children.

More serious illnesses

Sometimes, a high temperature in children is 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
• pneumonia – inflammation of the lung tissue, usually caused by an infection

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

Read more about recognising the signs of serious illness in babies and children.