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  • Writer's pictureDr Andy Raffles

Fever in Babies and Young Children (febrile illness/pyrexia)

At some point, your baby will almost certainly develop a high temperature. The average baby has around 7 viral illnesses a year, resulting in 7 episodes of fever. Many children have many more periods of fever than this, and it is not necessarily worrying. Fever is called febrile illness or pyrexia.

Signs of a fever are seeming unwell, warm, sweaty skin, a flushed face, perhaps with a rash, and a temperature of 38°C (100.4°F) or above. A baby's temperature can rise very quickly. This is a natural mechanism that helps the body fight infections.


Your baby's 'normal' body temperature is individual to him/her. Take a measurement when she is well so that you know what is normal It is recommend that electronic thermometers are used in the armpit, axilla, for taking temperatures and the values below are considered by NICE (National Institute for Health and Care excellence UK) guidance to be normal.

Under arm - 36.4°C (97.6°F)

In the mouth - 37°C (98.6°F)

Rectal – 37.6°C (99.6°F)

The current NICE definition of fever is a rectal temperature of 38°C (100.4°F) for a baby of under 3 months and 39°C (102.2°F) for older children, 3 month to 5 years or a temperature more than 0.5°C above normal for your child if taken by mouth or under the arm.

While your baby is feverish with a temperature of 38°C (100.4°F) below 3 months old; above 39°C (102.2°F) over 6 months of age he/she may be fretful and upset, hot and sweaty. He/she may or may not want to eat but may still drink or breastfeed.

The cause of fever is often infection in the ears, nose or throat, the digestive system or in the urine. Viruses are usually the cause and are self-limiting, disappearing without treatment Antibiotics have no effect on viral infections.

The goal is to stop the temperature from becoming higher. This will make your baby more comfortable and reduce the small risk that a rapid rise in temperature will lead to a febrile convulsion or fit.

How to do I treat a fever?

For a raised temperature, use the 'take temperature, treat temperature, take temperature' approach to determine whether your treatment is working. Give normal care, keep your child's room cool but avoid cold drafts. Keep him/her lightly dressed in cotton for comfort or take all clothes off.

Use paracetamol in the correct dosage to treat the fever and reduce pain. It cannot mask more serious symptoms. Use Ibuprofen, particularly at night as it is longer acting than Paracetamol, but do not use if there is a possibility of chickenpox as a cause of the fever. Paracetamol suppositories available on prescription in the UK or over the counter elsewhere in Europe, placed in the rectum are useful if your baby cannot take the oral preparation, or is vomiting. Offer favourite drinks, try to keep your child calm because crying or exertion may raise the temperature. Do not put a baby with febrile seizures in a bath. Aspirin containing preparations must not be used in childhood.

Good news, fevers generally get better within 3-4 days. However, if your child continues to have a high temperature or the rash does not settle, visit your doctor to exclude other illnesses including bacterial or urinary infections requiring antibiotic treatment. Because your child may be infectious it is best to keep her away from other children for 24 hours after the fever has cleared.

Be prepared:

  • Make sure you have a supply of Paracetamol at home

  • Keep telephone numbers handy of local health care services

Red Flag Symptoms - we advise you to seek help if symptoms include:

  • Fit or seizures associated with fever - febrile seizures

  • Uncontrolled crying and increased restlessness

  • A rash or bruising - particularly a rash which does not fade when a glass is pressed against it as this could indicate a severe bacterial infection

  • Difficulty breathing or grunting

  • Drowsiness or irritability

  • Fever related to heat/humidity exposure (heat stroke)

  • Ear pain(or ear rubbing)

  • Diarrhoea with every nappy change or has persistent diarrhoea and vomiting

  • Becomes limp and floppy. A very sick baby may not show a fever, but may feel cool or cold instead

  • Looks or acts sick and refuses feeds

  • If the temperature does not fall in response to the usual techniques. Your baby may get one illness closely followed by another, giving the impression that the fever is long lasting but it is best to be safe.

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