How do you get severe fever?

Your normal body temperature is approximately 37C. A fever is usually when your body temperature is 37.8C or higher. You may feel warm, cold or shivery.

You can find out if you have a fever by using a thermometer to take your temperature.

What causes a fever?

A fever is your body's natural response to many common illnesses such as:

• flu
• tonsillitis
• kidney or urinary tract infections (UTIs)

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

When to get help

If any of the following applies, please contact your GP practice:

• you have severe thirst or reduced urine output
• you are passing urine that is darker than normal
• you are light-headed or weak
• you have new, severe muscle cramps
• your symptoms have worsened or you notice new symptoms
• you've had a fever after recent foreign travel

If your GP practice isn't open, phone NHS 24's 111 service.

Fever and underlying health issues

Most fevers aren't in themselves life-threatening, however there are certain times where you may need to seek medical advice.

If any of the following apply to you and you have a fever, please contact your GP practice immediately:

• You are on treatment for immune deficiency
• You are on immune-suppressant drugs, such as regular steroids, methotrexate, azathioprine or cyclophosphamide
• You are taking medication where you have been warned about a risk of a reduced immune system
• You are on, or recently completed, treatment for cancer, leukaemia or lymphoma
• You are a transplant recipient
• You are HIV positive

Fever and your medical history

If you have a fever and any of the following medical conditions you should contact your GP practice immediately.

• Chronic lung disease
• Asthma which has been treated with medication in the last 3 years
• Heart disease (excluding blood pressure which is currently well controlled)
• Diabetes or another metabolic disease
• Chronic gastrointestinal or liver disease
• Chronic renal (kidney) disease
• Cystic fibrosis
• Neurological conditions such as cerebral palsy, stroke, multiple sclerosis or muscular dystrophy
• Sickle cell disease

Treating a fever

Most fevers will improve of their own accord in a few days. However, there are a number of things you can do to help the uncomfortable feelings associated with a fever.

1. Don't over dress. Wear loose comfortable clothing and make sure the room you are in isn't too warm. You shouldn't attempt to make yourself feel cold.
2. Drink more fluids, avoiding alcohol as this can make dehydration worse. You sweat more when you have a fever and drinking water makes sure you won't get dehydrated. You should be passing urine approximately every 6 hours. A pale yellow urine means you're unlikely to be dehydrated.
3. Take a medicine that reduces fever such as paracetamol (unless you're allergic or have been told by a healthcare professional that you can't take it).

Fever in children

Fever affects people of all ages, however it often affects babies and younger children in response to minor illnesses such as:

• Coughs
• Colds

Find out more about fever in children.

Fever in adults self-help guide

Self-help guide

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Last updated:
19 May 2022

Spot the symptoms of fever in your child and learn when a fever is too high. Read on to find out the causes of fever in children, and what you can do to bring it down.

What is a Fever in a Child?

A normal, healthy person has a body temperature around 37 degrees Celsius. A fever occurs when your child’s body temperature is higher than normal. Normal body temperature varies a little but a temperature above 38◦C is considered a fever.  A fever in young children usually means that they have an underlying infection.  The immune system raises the body temperature as part of a defence against infection. 

A fever can happen suddenly and it may not be easy to pinpoint its cause.

How to Measure Your Child’s Temperature

Choose a thermometer that is easy to use depending on the age of your child:

• Axillary (armpit) thermometer for children less than 4 weeks old 
• Axillary (armpit) thermometer, tympanic (ear) thermometer for children 4 weeks old and above
• Rectal thermometer, this gives the most accurate reading but is invasive and less convenient to use

Common Causes of Fever In Children

The most common causes of fever in children are viral infections. There are other less common causes.

Viral Infections

3. Gastroenteritis (Stomach Flu): vomiting, diarrhoea, stomach ache, dehydration

4. Hand, Foot and Mouth Disease: blister-like rash on the palms, soles, buttocks, tongue and mouth

5. Dengue Fever: headache, muscle and joint aches, rash

6. Chickenpox: blister-like rash on the body

Bacterial infections

These are less common than viral infections but can also cause fevers. e.g. pneumonia, urinary tract infections (foul-smelling urine and decreased urine production) and  kidney infections.

Immunisations

Sometimes, children develop a fever after an immunisation e.g. after DTaP. Immunisations are designed to stimulate the immune system to develop immunity to a specific bacteria/virus. Fevers following immunisation are not usually prolonged.

Inflammatory Conditions

Inflammatory conditions and reactions e.g. Kawasaki Disease (presents with prolonged fever, red eye, body rash, swelling of the lips/ tongue/ feet/ hands, lymph nodes in the neck) , some types of arthritis e.g. Juvenile Idiopathic Arthritis or tumours may also cause fever.

Do note that teething in babies usually does not cause high fever.

When Should You Bring Your Child to the Doctor?

Fever can be scary, especially if your child is very young, or if his fever is persistently high for a few days. A higher temperature does not mean a more severe illness. Fever is a symptom of an underlying disease and a sign that the body is fighting the disease.

Depending on your child's age, look out for changes in his behaviour when deciding whether and when, to bring him to the doctor. If your child appears well, responsive and can take feeds or eat despite running a fever, let him rest and sponge him to keep his temperature below 38˚C. Use your instincts.  If you are concerned or think your child is getting worse, please seek medical attention for your child. 

Go to the Children's Emergency immediately if your child:

• Has a temperature of more than 41.0°C, or 38.0°C for those less than 3 months old
• Is difficult to awaken. Fever may make children sleep more but they should awaken easily and be able to respond to you
• Seems confused or delirious
• Cries constantly and you cannot settle him or her
• Has difficulty breathing
• Is very lethargic
• Has a skin colour that appears pale or grey
• Has bruising spots
• Has a fit (seizure or convulsion)
• Is drinking less fluids and has significantly less urine output than usual 
  

What is a Febrile Fit? 

Febrile Seizure:

Children between the ages of 6 months and 6 years may experience febrile seizures (fits) especially if the fever is persistently high. Approximately a third of the children who have had a febrile seizure may develop another episode in future. Fortunately, most children with febrile seizures do not develop any brain injury or epilepsy. Common signs of a febrile seizure include the following when the child has a fever:

• Jerking or shaking of limbs
• Loss of consciousness
• Foaming at the mouth
• Uprolling of the eyes, so only the whites of the eyes are visible
• Biting of tongue
  

Related: Give Your Child the Best Protection

Fever Treatment: What can I do if my child has a fever/high temperature? 

To help your child feel more comfortable, here's what you can do to bring down his temperature:

1. Sponge him with lukewarm water. Do not sponge your child with ice water or cold water, or for more than 30 minutes at a time.

2. Dress your child in thin clothing and cool the room. Do not wrap him in thick blankets to "sweat it out" as it will prevent him from losing heat.

3. Let your child rest more and drink lots of fluids to avoid dehydration.

4. Seek medical advice and serve the prescribed dosage of fever medications like paracetamol and ibuprofen (provided your child has no allergies) if his fever remains above 38.5 degrees Celsius. Do note that paracetamol and ibuprofen do not treat the cause of the fever

It is reassuring if a child improves with when the temperature comes down.

Disclaimer: The information provided in this article is meant purely for educational purposes and may not be used as a substitute for medical diagnosis or treatment. You should seek the advice of your doctor or a qualified healthcare provider before starting any treatment or if you have any questions related to your health, physical fitness or medical condition.

Related: Fever

Visit Parent Hub, for more useful tips and guides to give your child a healthy start.

Learn more about the other common conditions that children face:

• Asthma
• Diarrhoea
• Constipation
• Coughs and Colds
• A Child-Safe Home
  

This article was last reviewed on Thursday, September 2, 2021

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