Welcome to The Art of Patients. I’m Dr Golly and today we’re talking fevers in children. This is one of the most common concerns for parents, because fevers can disturb how your child eats, drinks, sleeps and behaves. Sudden spikes can even result in seizures. It’s hard to know when to treat and when to worry.
Doctors sometimes refer to fever as febrile illness or pyrexia, coming from the Latin word purexis, meaning fire. It’s a very common sign of illness, not an illness in itself – and it’s perfectly fine if your child experiences a fever as often as once a month, lasting less than 48 hours. But remember – any child with a fever under the age of 3 months definitely needs to be seen by a doctor.
Let’s jump to the whiteboard and discover just how an illness causes a fever. By far the most common cause of fever in children is an infection, caused by a bug. Through complex pathways, chemicals are released that travel to a special part of the brain, called the hypothalamus – this is the body’s thermostat. These chemicals turn down the body’s thermostat temperature, tricking the body into thinking it’s cold. Then the body reacts by increasing its temperature, which is why you ‘feel’ cold, even though you might be burning up on the outside.
Things like exercise, hot weather and teething don’t cause a true fever, despite your child feeling warm to touch. Newborn babies, up to 3 months of age, are at risk of low – or unstable – temperatures too, but today we’re going to focus only on children 3 months and older. So with all this talk of fevers – how do we measure a child’s temperature?
Different measuring machines have different ranges – unfortunately for bub, the single most accurate way to check a baby’s temperature is with a rectal thermometer. But we don’t recommend this method because it’s difficult, kids don’t like it – and there’s a risk of causing injury.
An armpit measure is usually the safest but it’s also the least accurate, measuring up to 1 degree lower than the true body temperature. Oral thermometers are only suitable over the age of 5, in case the child bites down and ends up with a mouth full of glass and mercury. Ear thermometers are great, but make sure the ear canal is not full of wax, which can distort the reading.
So – for armpits, anything over 37.3 is a fever.
For oral measurements, the limit is 37.5.
And for ear thermometers, it’s 38.
Newer, infrared thermometers give very accurate measurements and have the benefit of not touching the skin, but these are pricy toys to buy.
Treat your child by removing excess clothing and patting them down with a damp towel. Don’t use cold baths because of the risk of drowning or hypothermia. Encourage small sips of clear fluid to keep them hydrated and don’t worry if they’re off their food.
The red flags that need a medical review are:
- a child under the age of 3 months;
- a temperature higher than 40 degrees;
- persistent vomiting or diarrhoea;
- dehydration from not drinking;
- a persistent headache or sore, stiff neck;
- a child looking increasingly sick or drowsy; or
- if you’re worried for any other reason.
We treat fever to try make children more comfortable and able to eat, drink and sleep like normal – but not all fevers need to be treated. Fever from infection is rarely harmful – though very high and/or prolonged temperatures should be investigated by a doctor, because it may represent a more worrying, underlying problem.
If you decide to give medication, the safest and most effective medicines are paracetamol and ibuprofen. They have different mechanisms of action, which means you can give them both at the same time – just be careful to follow the dosing and frequency instructions on the label, because they’re very different.
Whilst adults use aspirin frequently, this is not a medicine you should be giving children.