What is a fever (high temperature) in children?

As a general rule, a temperature of over 37.5C (99.5F) is classified as a fever.

You can use a thermometer to find out if your child has a fever. For more information, see How do I take someone’s temperature?

Causes of fever

Most fevers are caused by an infection or another illness.

Fever helps your body fight infections by stimulating the body’s natural defences. By increasing the body’s temperature, a fever makes it harder for the bacteria and viruses that cause infections to survive.

There are many conditions that can cause fever. Most fevers are cause by a viral illness that will get better by itself without any specific treatment. Occasionally a fever may be caused by more serious infection, such as pneumonia or meningitis.

Don’t try to reduce your child’s fever by over or under dressing them, or sponging them with water. You can use paracetamol or ibuprofen to treat any distress or discomfort caused by the fever and being unwell. Read more information about treating a high temperature and giving your child paracetamol and ibuprofen.

Getting help

If you’re worried about your child, trust your instincts. Speak to your GP or call NHS 111 and speak to an advisor.

If your GP surgery is closed, contact their out-of-hours service. You will be informed about how to do this when you ring your GP’s phone line. If you’re still concerned, or if your GP or out-of-hours provider isn’t available, take your child to the nearest hospital’s accident and emergency (A&E) department.

Symptoms of serious illness

Symptoms that may be a sign of a more serious illness include:

• being unusually sleepy
• poor feeding
• having a non-blanching rash (a rash that doesn’t fade when a glass is pressed firmly against the skin; this is known as the glass test)
• a continuous or high-pitched cry

For more signs of serious illness and advice on when to call an ambulance for your child, see Recognising signs of serious illness.

Febrile seizures

Febrile seizures (or fits) sometimes happen in children who have a high temperature, but are a rare occurrence. Read more about febrile seizures.

Read the answers to more questions about children’s health.

Further information:

• Can I give my child painkillers?
• How do I take someone’s temperature?
• Febrile seizures
• Flu
• Tonsillitis
• Recognising signs of serious illness
• Treating a high temperature
• NHS vaccination schedule