Fever in children – when can you wait and see, and when should you contact a doctor?

By pediatrician Anette Broen Sandmo

A small child with a fever of 39 or 40°C can make most parents worried. Fortunately, fever in children is most often caused by common and harmless viral infections.

The most important thing is not necessarily how high the temperature is, but how the child is doing.

In fact, high fever says little or nothing about how serious the illness is or the prognosis going forward. Low fever does not rule out a serious infection.

An example: Petter, age 3, can have a fever of 40.6°C from a common viral infection. Lene, age 2, can have a fever of 38.4°C and be critically ill.

As a pediatrician, I am therefore more interested in the child's general condition than the number on the thermometer.

Here you'll find answers to the most common questions about fever in children, what you can do yourself at home, and which signs mean the child should be seen by a doctor.

What is fever?

Fever is defined as a body temperature of 38.0°C or higher. Temperature measured rectally is considered the most accurate measurement method. It is difficult to determine with certainty whether a child has a fever just by feeling their forehead.

Children get high fevers more easily than adults, and can have temperatures of both 39 and 40°C from completely ordinary viral infections.

Fever is not an illness in itself, but part of the body's natural defense against infection. When the immune system is activated, the body's "thermostat" is turned up, and the temperature rises.

What causes fever in children?

The most common cause of fever in children is self-limiting viral infections, for example colds, influenza, RSV, or gastroenteritis.

Fever can also be caused by bacterial infections such as ear infections, throat infections (although throat infections in children are usually viral), pneumonia, or urinary tract infections. More serious bacterial infections such as blood poisoning (sepsis) and meningitis fortunately occur far less often.

In young children, it can be difficult to know where the infection is located. Sometimes fever is the only clear symptom during the first hours or the first day.

Is the child seriously ill?

There is no single specific temperature that alone tells you how sick a child is.

When I assess a child with fever, the child's general condition is one of the most important things.

Ask yourself:

• Do I get good contact with the child, or does it seem unusually listless and apathetic?
• Is the child able to drink?
• Is the child urinating roughly as usual? Does a child in diapers still have regularly wet and heavy diapers?
• Does the child have normal skin color?
• Is the child breathing calmly, or does it seem to be struggling to breathe?
• Does the child have periods where they perk up, smile a little, make better contact, or manage to play?
• Is it possible to comfort the child?

Parents' gut feeling is important, and is often right. You know your child best. If the child seems clearly different than usual, or you sense that "something isn't right," it is right to contact a doctor.

Can infants get fever?

Yes. A child under three months old with a temperature of 38.0°C or higher should be seen by a doctor.

In such young children, fever can be the only sign of a serious infection, so the threshold for a medical examination should be low.

This is one of the situations where you should not wait until the next day to see how things develop.

When can you generally wait and see at home?

In a child older than three months, fever can usually be monitored at home if the child:

• has good contact
• is getting fluids
• is urinating regularly
• is breathing without difficulty
• has normal skin color
• does not have severe pain or other alarm symptoms
• has periods where they seem relatively comfortable or perk up a little

So it is not necessary to contact a doctor just because the thermometer shows 39 or 40°C.

What can you do at home?

Offer fluids often

Children with fever need more fluids than usual. Offer small amounts often. Water, milk, breast milk, juice, ice cream, or other drinks the child accepts are all fine when the child is sick.

I usually say that a good "receipt" that the child is getting enough fluids is that they are still urinating regularly. In small children, you can keep track of whether the diapers are still heavy and wet.

Let the child be as comfortable as possible

A sick child needs, above all, a safe adult nearby. Be close. Slow down the pace. The child needs rest and quiet.

Let the child be lightly dressed and keep the room at a comfortable temperature.

Food is less important than fluids

Many children eat little when they have a fever – a full dinner plate is rarely tempting when you're sick.

Feel free to offer small amounts of food the child likes, but don't worry if the appetite is poor for a few days. Fluids are more important than food in the acute phase.

When should you give Paracet (paracetamol) or Ibux (ibuprofen)?

A child does not need to become fever-free. The goal of fever-reducing medicine is primarily for the child to feel better, not for the thermometer to show a normal number. Many children perk up a bit when given fever reducers, and manage to drink, eat, and play.

Fever-reducing medicine can be useful if the child:

• seems clearly distressed or in pain
• can't sleep due to discomfort
• is drinking poorly because they feel unwell
• has pain in the throat, ears, or body

Paracetamol is usually the first choice and should be dosed according to the child's weight. Follow the recommended dosage on the package or advice from a doctor or pharmacy.

Ibuprofen can be used in many children, usually from six months of age, but is not suitable in all situations. It should, among other things, be avoided if the child is dehydrated, for example due to a lot of vomiting or diarrhea, and should not be used for chickenpox.

Remember: Fever-reducing medicines do not prevent febrile seizures.

When should you contact a doctor or emergency clinic the same day?

• the child is under three months old and has a temperature of 38.0°C or higher
• the child seems markedly listless, worn down, or difficult to make good contact with
• the child won't or can't drink
• the child is urinating significantly less than usual
• the child is breathing rapidly. Remember that breathing rate depends on the child's age; a breathing rate of, for example, 40 per minute is normal for a baby, but far too high for a 3-year-old
• the child seems to be struggling to breathe: pulling in between or under the ribs, using a lot of effort to breathe, grunting, or having trouble talking, eating, or drinking due to the breathing
• the child has strong or persistent pain
• the child has a febrile seizure for the first time
• the child first seems better, but then clearly worsens again – this can be a sign of secondary bacterial infection
• you as a parent feel that something isn't right

When should you call 113 (emergency)?

Seek emergency medical help if the child:

• is difficult to wake or has reduced consciousness
• has pronounced breathing difficulty
• turns gray or bluish in the skin
• has a febrile seizure lasting more than five minutes
• has neck stiffness, severe headache, repeated retching or vomiting, and at the same time seems seriously ill
• gets red or purple spots or a rash that does not fade when you press a glass against the skin, especially if the child also seems seriously ill

Is a fever of 40°C dangerous?

Not necessarily. High fever itself is rarely dangerous in otherwise healthy children. As mentioned, the number on the thermometer alone says little about the severity of the illness.

Can fever damage the brain?

No. Ordinary fever caused by an infection does not damage the brain.

This should not be confused with dangerously elevated body temperature due to overheating, such as heatstroke, which is a different condition.

What are febrile seizures?

Some children between roughly six months and five years of age can have seizures in connection with fever. It can look very dramatic, but ordinary febrile seizures are usually harmless and do not cause brain damage.

If a child has a seizure, stay with the child, place them on their side, make sure they can breathe freely, and do not put anything in their mouth.

The first time a child has a febrile seizure, the child should be seen by a doctor. If the seizure lasts more than five minutes, call 113.

Fever-reducing medicines such as paracetamol or ibuprofen do not prevent febrile seizures.

How high can the fever get?

With ordinary infections, body temperature rarely exceeds 40.5–41.0°C. The body's own "thermostat" in the brain will regulate and slow the fever response before it becomes harmful.

Do I need to wake the child to give fever-reducing medicine?

Usually not. You don't need to wake a child who is sleeping well just to give fever-reducing medicine.

With high fever, however, it can be wise to check on the child a couple of times during the night and make sure the child can be woken and that you get good contact.

How long can a child have a fever?

Many common viral infections cause fever for a few days. How the child is doing and how the illness develops is more important than a specific number of days.

If the fever persists for 3–4 days with no sign of improvement, the child should be seen by a doctor. The same applies if the child first seems to improve, but then gets a new fever or clearly worsens again.

Does the child need to eat?

No. It is common for children to eat significantly less when they have a fever.

Feel free to offer small portions and food the child likes, but don't pressure the child to eat. The most important thing in the first few days is that the child gets fluids and is still urinating.

When can the child go back to daycare?

Children with fever should stay home. The child can usually return to daycare when they are fever-free and their general condition is good enough that they can manage a normal day at daycare. A fever-free, quiet day at home is often recommended before sending the child back to daycare.

Finally

The vast majority of fever episodes in children are caused by common viral infections and resolve on their own.

As a parent, you don't primarily need to chase a specific number on the thermometer. Look at the child: Do you get good contact? Is the child drinking? Urinating? Breathing well? Does the child have periods of perking up?

And remember that you know your child better than the doctor meeting them for the first time. If the child behaves clearly differently than usual, you sense that something isn't right, or you as a parent are worried, it is right to seek a medical assessment.

Anette Broen Sandmo
Specialist in Pediatrics