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 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. A fever helps the body 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:

• upper respiratory tract infections (RTIs)
• flu
• ear infections
• roseola (a virus that causes a temperature and rash)
• tonsillitis
• kidney or urinary infections
• 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 due to 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 38°C (101°F) or above
• is between three and six months old and has a temperature of 39°C (102°F) or above
• is over six months old and, as well as a fever, has other signs of being unwell, such as floppiness and 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 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 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 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)
• give them children’s 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. These are painkillers that also act as antipyretics, meaning they help to reduce fever

Antipyretics aren’t always necessary – for example, if your child isn’t distressed by the fever or underlying illness.

Always read the patient information leaflet that comes with the medication, when using antipyretics, 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
• urinary tract infection (UTI)
• pneumonia – inflammation of the lung tissue, which is 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.

The Map of Medicine is used by doctors throughout the NHS to determine the best treatment options for their patients. NHS Choices offers everyone in England exclusive and free access to this cutting-edge internet resource, which lets you see exactly what your doctor sees.

The information in the Map has been approved by the UK’s leading clinical experts, is based on the best available clinical evidence, and is continually updated. To take advantage of this unique resource go to:

Map of Medicine: fever in infants and children under age 5 years