Why does my child have a fever?

A high temperature or a fever is very common in children, and it’s typically a sign that their body is fighting an infection, like a cold, chicken pox or tonsillitis. They may also develop a fever after a vaccination – we know, the tears from that painful needle were bad enough, now you’ve got an unsettled, feverish child on your hands!

If your child has a high temperature, it usually isn’t anything to worry about. A fever can be the result of many different things, but it’s helpful to know what’s causing it in order to find the most effective treatment.

In this guide we’ll discuss what a fever is, the symptoms in children, the potential causes, and how you can lower your child’s high temperature at home. After all, it’s impossible to relax when your little one isn’t their usual self! Hopefully, with the useful advice in this guide, they’ll be right as rain in no time.

What is a fever?

A fever is classified when you or your child’s body temperature reaches 38°C or higher. The normal temperature for babies and children is around 36.4°C, but as every child is unique, this number can vary.

When your child’s body temperature rises, it’s just their immune system’s normal response to fighting off an infection or illness. To determine whether they have a high temperature, you can check their temperature with a thermometer (you can find some reliable ones listed below), or you can look at their symptoms. They may feel hotter than usual when you touch their back or chest, have flushed cheeks, feel sweaty, and look or feel unwell. They may complain of feeling cold or shivery, too.

The causes of a fever

To decide the cause of your child’s fever, you need to look at the other symptoms they're displaying and the context. For example, if they have a cough and a runny nose, they likely have a cold. Whereas if they’ve recently had a vaccination, that’s probably the cause of their fever, not an illness. Possible infections and illnesses that can cause a fever are:

  • Cold and flu
  • Ear infections
  • Upper respiratory tract infections (RTIs)
  • Roseola, a virus that causes a high temperature and a rash
  • Kidney or urinary tract infections (UTIs)
  • Tonsillitis
  • Chicken pox
  • Whooping cough
  • Coronavirus
  • Vaccinations

How to tell if your child has a fever

The easiest way to tell whether your child has a fever is to take their temperature. You can do this with a digital thermometer or an in-ear thermometer in older children.

If you're taking the temperature of a child younger than 5 years old you should always take their temperature under their armpit. Not only is this a quick way to get a reading, it's the safest and most accurate way to take a young child's temperature at home.

If you have an older child, you may consider using an in-ear thermometer to take their temperature. However, you should make sure you're confident in using the thermometer properly, as they can give inaccurate readings if they are not inserted into the ear properly.

Spotting signs of a fever without a thermometer

Don't worry if you don't have a thermometer to hand right away, there are a couple of signs you can look for that could indicate that your child has a fever.

For starters, they may look flushed, or be shivery, which are indicators that their body is actively trying to lower their temperature.

Try comparing your temperature with your child's by touching your own forehead with the back of your hand before doing the same to their forehead. This will help you to judge whether they feel hot or not.

Other symptoms you may notice when your child has a fever include:

  • Irritability
  • Lethargy
  • Flushed or pale skin
  • Difficulty swallowing
  • Refusal to drink or eat.

When to see a doctor

Of course, there will be other illnesses and infections that might be causing your little one’s fever. Although it’s likely that their fever will get better with rest and treatment from home, it’s important that you seek medical advice if:

  • Your child is under 3 months old and has a temperature of 38°C or more, or you think they have a high temperature
  • Your child is 3 to 6 months old and has a temperature of 39°C or more, or you think they have a high temperature
  • They have other signs of illness, such as a rash
  • They have had a high temperature that's lasted for 5 days or more
  • They do not want to eat, or is not their usual self and you're worried
  • Their high temperature doesn’t come down with paracetamol
  • They are dehydrated. For example, their nappies are not very wet, they have sunken eyes, and no tears when they're crying

Alternatively, you must seek emergency medical attention if:

  • Your child has a stiff neck
  • They have a rash that does not fade when you press a glass against it
  • They are bothered by light
  • They have a fit (febrile seizure) for the first time.
  • They have very cold hands and feet
  • They have blue, pale or blotchy skin, lips or tongue
  • They have a weak, high-pitched cry that's not like their normal cry
  • They are drowsy and difficult to wake
  • Your child is extremely agitated or confused
  • They are finding it hard to breathe and suck their stomach in under their ribs
  • They are not responding like they normally do, or are uninterested in feeding or normal activities

How to lower your child’s fever

When your child has a temperature, there are some things you can do to help bring it down and break the fever, like:

  • Giving them plenty of fluids to prevent dehydration
  • Giving them food if they’re hungry
  • Checking on them regularly during the night
  • Keeping them at home
  • Giving them paracetamol or ibuprofen, like Calpol or Nurofen for Children

There are some things you shouldn’t do, too, like:

  • Undressing them or sponging them down to cool them
  • Covering them up in too many clothes or blankets

When your little one is burning up with a fever, it’s natural to be concerned. Thankfully, a fever just means that their immune system is fighting off a nasty infection or illness, and it’s doing its job as it should!

A high temperature can usually be treated at home, but there are times when a fever can be a sign of something more serious, so always get medical attention if they’re showing any alarming symptoms. If you need further information about why your child might have a fever, visit the NHS website.

Alexandra Moses - Medical Content Writer
James O'Loan - CEO & Superintendent Pharmacist
James O'Loan , CEO & Superintendent Pharmacist on 21 March 2023
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