Fever in Children

Fever in children means the body temperature has risen above normal, and it almost always points to an infection somewhere. For most parents, fever is the signal that the child is ill and that the night’s sleep will be broken. Yet fever is the immune system’s response to an infection: it is the body’s answer rather than the illness itself.

This page explains how fever develops, how a thermometer should be used, what does and does not help a child with a fever, and which signs call for urgent assessment. Every decision about your child’s fever belongs to the doctor.

How fever arises in children

Body temperature is regulated by a centre in the brain. When an infection is met, the immune system raises that centre’s set point by a degree or two, by increasing heat production and narrowing the blood vessels of the skin so that germs find it harder to multiply. Fever is a defence mechanism.

This mechanism comes into play more easily in children, particularly in babies, because temperature regulation has not yet matured. The same infection may produce a different height of fever in two children.

The most common causes of fever in children are respiratory infections, urinary tract infections, bowel infections and skin infections. Fever can also follow a vaccination, come with teething or appear in some inflammatory conditions. It is therefore not accurate to say that fever is always caused by an infection; where it lasts longer than a week, a doctor should assess it.

How should a thermometer be used?

Digital thermometers measure the temperature of the area they are placed on, so results from the armpit, the ear, the forehead and under the tongue can differ from one another.

• The armpit is the method most often used in small children. The thermometer should sit flat against the skin and be held in place while the child rests with the arm closed.
• The ear is practical in older children, though the shape of the ear canal and the position of the child can affect the reading.
• The forehead is quick, but sweating, the temperature of the room or a flushed face can alter the result.
• Taking the temperature by mouth is not reliable in small children, who may swallow the thermometer or be unable to hold their breath.
• When in doubt, measuring again by a different method is always the right move. How the child looks, how they are breathing and whether they are drinking all count alongside the number.

What does making a child comfortable with fever mean?

Bringing the temperature down and making the child comfortable are not the same thing. The aim is to improve how the child feels, not to chase a number; a fever reducer is used as the doctor advises.

The most common mistake here is waking a sleeping child in order to give a fever reducer. What exhausts a child is not the height of the fever but the way it makes them feel. If the child sleeps easily and their breathing is regular, waking them is often unnecessary. If they seem listless when you wake them, or if any of the warning signs below are present, they should be woken and assessed.

Similarly, it is not right to keep giving medicine to a child whose fever has come down. The purpose of the medicine is to relieve discomfort, not to return the temperature to a normal figure.

Appetite usually falls when a child has a fever, and this is normal. Offer fluids little and often and give the foods the child accepts rather than pressing a solid diet. Signs of dehydration, such as a dry mouth or fewer wet nappies, should be reported to the doctor.

Using a fever reducer safely

• Different fever reducers should not be alternated. Using paracetamol and ibuprofen in turn can lead to confusion over which medicine was given when, and to too much medicine being given by mistake, so it should not be done without asking your doctor; the doctor decides which product to use and how often.
• Only preparations suitable for children should be used; the choice depends on age and on the doctor’s advice.
• Aspirin should not be given to children.
• The body should not be rubbed with alcohol or cologne: the cooling is only temporary and the skin may be irritated.
• Ice and cold compresses should be avoided. If a child shivers, this can push the temperature up again.
• The child should be lightly dressed in a cool but ventilated room; heavy covers should be avoided.

Which signs need urgent assessment?

If any of the following is present, do not keep watching the fever at home; call 112 or go to the nearest emergency department immediately:

• Stiff neck, severe headache or confusion.
• A rash that does not fade when pressed, purple colouring, or one that spreads very quickly.
• Severe difficulty breathing, the chest pulling in between the ribs or bluish lips.
• A seizure (fit) or loss of consciousness.
• A child who seems completely indifferent to their surroundings or is hard to wake.

In the following situations, the child should be seen by a doctor the same day:

• Marked tiredness, restlessness or difficulty settling.
• Repeated vomiting over a long period, a swollen abdomen or not passing urine.
• Marked weight loss in a short time, or a clear drop in the desire to feed.

When to see a doctor, and how to follow a fever at home

Most fevers settle within a few days, and watching through that period is usually the right approach. If a baby under three months of age has a fever, however, see a doctor or go to an emergency department without delay, whatever the baby looks like. In the following situations, an appointment should be booked.

• The fever lasts longer than three days, or appears to settle and then returns.
• The child is clearly affected by poor sleep, poor appetite or listlessness.
• Infections follow one another in quick succession.
• A fever after a vaccination continues for longer than the expected period.
• The symptoms accompanying the fever change, because that signals a change in the course.

It helps to write down the highest and lowest readings of the day, the child’s appetite and sleep, and the medicines given with their times. This record is the most useful tool for the doctor in assessing the picture.

Common mistakes

1. Becoming fixated on the number and losing sight of the child. Panicking when the reading is high, or assuming all is well because it has come down, are both wrong.
2. Giving a fever reducer at every reading. The medicine should not be used more often than the doctor has indicated.
3. Rubbing the child with alcohol, cooling with ice or covering them heavily. These make the child uncomfortable and can set off shivering that makes the situation worse.
4. Taking antibiotics. Most fevers are caused by viruses, and antibiotics do not act against viruses.
5. Waiting to see whether the fever settles “for one more day”. If any of the warning signs above are present, the period of waiting should not be extended.

Common questions

Should I wake a sleeping child with a fever to give a fever reducer?

Generally there is no need. Waking a child who sleeps comfortably adds tiredness and agitation, whereas the discomfort itself is what tires a child out. If the child seems listless when you wake them, or their breathing is uncomfortable, they should be woken and seen by a doctor.

Can I alternate between fever reducers?

Not without asking your doctor. Using paracetamol and ibuprofen in turn can lead to confusion over which medicine was given when, and to too much medicine being given by mistake. Follow the doctor’s instructions about the product, the interval and the duration.

At what temperature does a child have a fever?

A body temperature of 38 degrees and above is generally taken as a fever. Because the reading changes with the part of the body measured, knowing the method matters more than remembering a single figure.

My child’s temperature has come down. Should I keep giving the medicine?

No. The medicine is given to relieve discomfort, not to drive the temperature down further. It should not be given more often than the doctor has indicated, and once it is stopped it is worth watching whether the child becomes uncomfortable again.

When is a fever in a baby an emergency?

A fever in a baby under three months needs to be seen by a doctor or in an emergency department without delay, however well the baby appears, because the signs may be unclear and an infection can progress quickly. In older children, the warning signs listed above and the length of the illness guide the decision.