Causes of fever and high temperature in children
A normal temperature range for children is 36.5°C-38°C. A fever is when your child’s body temperature is higher than 38°C.
Fever is not an illness in itself, but is the sign of an illness.
Children get fevers for all kinds of reasons. Most fevers and the illnesses that cause them last only a few days. But sometimes a fever will last much longer and might be the sign of an underlying chronic or long-term illness or disease.
Infections are by far the most common cause of fever in children. In general, fever is nature’s response to infection. It’s a good sign that your child’s body is fighting the infection.
Most childhood infections are caused by viruses, which are responsible for common colds and other upper respiratory tract infections, as well as the common infectious diseases of childhood, like chickenpox. These infections don’t last long and usually don’t need to be treated.
Some infections are caused by bacteria, which need treatment with antibiotics. These include certain ear and throat infections, urinary tract infections, pneumonia, blood infections and meningitis. A very sore throat with a fever can be caused by Streptococcus. If it isn’t treated with antibiotics, this infection can be dangerous and lead to things like rheumatic fever or heart damage.
There are other less common causes of fever. These include allergic reactions to drugs or vaccines, chronic joint inflammation, some tumours and gastrointestinal diseases like gastroenteritis.
During the course of each day, body temperature goes up and down by up to 1°C. It’s usually lowest in the early hours of the morning, and highest in the late afternoon and early evening.
A fever or high temperature might come on slowly and rise over a few days, or it might rise very quickly. These things usually don’t have anything to do with the illness that causes the fever.
Fever in itself is rarely harmful. But the high temperature might make your child feel uncomfortable – he might have chills or shivering when his temperature is rising, and he might sweat when it’s falling. Sometimes he might become mildly dehydrated if he’s losing a lot of fluid from the fever and not drinking enough.
Febrile convulsions are seizures that can happen because of a high fever. They occur in about 3% of children between the ages of six months and five years. Children almost always outgrow febrile convulsions by the age of 4-5 years. Febrile convulsions have no long-term consequences, but if your child has a febrile convulsion, it’s best to talk to your GP about it.
When to see your doctor about fever and high temperature
Babies under three months of age who develop a fever must be seen by a doctor immediately, because it’s harder to tell whether they have a serious underlying illness.
In children aged 3-12 months, fever might be a sign of a more significant illness, so seek medical advice within the same day.
In children over 12 months, seek medical attention if your child has a fever and:
- looks sicker than before – more pale, lethargic and weak
- has trouble breathing
- becomes drowsy
- refuses to drink, and is weeing less often (if your child has fewer than half the usual number of wet nappies, see a doctor)
- complains of a stiff neck, persistent headache or light hurting her eyes
- vomits persistently, or has frequent bouts of diarrhoea
- doesn’t improve in 48 hours
- suffers pain
- is causing you to worry for any other reason.
You should treat a fever only if it’s making your child uncomfortable. A fever will run its course regardless of treatment.
Generally, children handle fever well, but you can do a few things to make your child more comfortable:
- Dress your child in light clothing.
- If your breastfed child is younger than six months, offer him extra breastfeeds.
- If your formula-fed child is younger than six months, offer her the usual amount of formula. You might need to feed her smaller amounts more frequently.
- If your child is older than six months, keep breastfeeding or bottle-feeding. You can also offer your child clear fluids like water. If your child isn’t hungry while he has a fever, that’s OK.
- Give your child liquid paracetamol in the recommended dose and frequency. If your child has more than the recommended dose it can cause liver damage. You can also give ibuprofen to children aged over three months. Don’t give fever-lowering medication too often or for too long, because it can cause side effects.
- Avoid cool baths, sponging and fans. These can actually make your child more uncomfortable.
If your child has a fever, the most important thing is to make sure she’s drinking enough to avoid dehydration. If you’re worried your child isn’t drinking enough, speak with your GP.