Fever

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When to see the doctor

Seek medical attention if your child:

• looks sicker than before
• has difficulty breathing
• becomes drowsy
• refuses to drink, and is urinating less frequently; if your baby has less than half the usual number of wet nappies, see the doctor
• complains of a stiff neck, persistent headache or light hurting their eyes
• vomits persistently, or has frequent bouts of diarrhoea
• does not improve in 48 hours
• is aged less than 12 months and has a fever
• is causing you to worry for any other reason.

A child's average body temperature is about 37°C (98.4F). During the course of each day, the body temperature will vary by a degree or two. It is usually lowest in the early hours of the morning, and highest in the late afternoon and early evening.

If your child's temperature is higher than 38C for 24 hours or more, he probably has a fever. A child may have a slightly raised temperature for a brief period of time for many reasons, including increased physical activity.

Using a thermometer is the best way to check a child's temperature. Feeling a child's skin temperature (for example, by putting lips to the forehead) is not always a reliable way of diagnosing a fever. Sometimes a child may appear flushed, and their skin may feel warm, but the child's core (or inner body) temperature will in fact be quite normal. This can happen when they have a cold or have engaged in vigorous physical exercise. It can also occur on a very hot day.

What causes it?

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, only last a few days. Sometimes a fever will last much longer, and may 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. Most of these are caused by viruses, which are responsible for colds, upper respiratory infections, and the common infectious diseases of childhood such as chickenpox. These infections don't last long and usually don't need to be treated. In general, fever is nature's response to infection, and can actually help the body to fight infection.

Some infections are caused by bacteria, and need treatment with antibiotics. These include certain ear and throat infections, bladder infections, pneumonia, blood infections and meningitis. For example, a very sore throat with a fever can be caused by streptococcus, and if not treated with antibiotics can lead to rhumatic fever or heart damage.

Other causes of fever are relatively uncommon, and include allergic reactions to drugs or vaccines, chronic joint inflammation, some tumours, and gastrointestinal diseases.

How is it treated?

A fever will run its course whether or not it is treated. Fever is one of the ways the body has of fighting infection, and the temperature will return to normal when the infection or other cause of the fever has completely gone.

The fever should only be treated if you feel it is making your child uncomfortable, irritable or so lethargic that he is not drinking enough fluids. However, in children under the age of 12 months fever may be an indication of a more significant illness, and you do need to seek medical advice.

Babies under three months of age who develop a fever must be seen by a doctor immediately, as it is harder to tell if they have a serious underlying illness.Febrile convulsions or fits accur in about 4% of children between the ages of six months and five years. Children inevitably outgrow febrile convulsions by the age of 4-5 years. They have no long-term consequences, but talk to your doctor about them.

Fever in itself is rarely harmful. A high temperature may make your child feel uncomfortable — they may have chills or shivering when their temperature is rising, and may perspire when it is falling. Sometimes they may become mildly dehydrated, if they are losing a lot of fluid from the fever and not replacing it.

Generally children handle fever well. A fever may come on slowly, and rise over a few days, or it may rise very quickly. The height of a fever, and how quickly it comes on, do not usually have anything to do with how severe the illness is.

Here are some ways that a child with a fever can be made more comfortable:

1. Dress your child in light clothing.
2. Give them small quantities of clear fluids such as water, weak tea, or diluted soda water or lemonade to drink at frequent intervals. (Lemonade is too strong for a child with gastroenteritis with diarrhoea — it must be diluted.) If your child is not hungry it's OK - the most important thing is to make sure that they are drinking enough to avoid dehydration.
3. Give liquid paracetamol in the correct and recommended dose, with no more than five or six doses every 24 hours. Exceeding the recommended dose can cause liver damage. You can use ibuprofen instead (which lasts longer and does not compound with paracetemol). It's important not to give fever-lowering medication too often or for prolonged periods, as it can cause side-effects.

Cooling measures such as cool baths, sponging, use of fans may actually make your child more uncomfortable.

If you get a reliable thermometer and learn to take your child's temperature, you won't have to use unreliable methods like feeling the child's forehead. Your local doctor or maternal and child health or community nurse can show you how to take temperature with a thermometer.

Taking your child's temperature

Taking the temperature of a baby or young child is more difficult than it seems. There are several different methods for taking a child's temperature:

• orally (putting a digital thermometer in the mouth under the tongue)
• rectally (putting the thermometer a little way into the baby's rectum)
• axillary (under the armpit)
• aurally (with a digital ear thermometer — shown to be a little inaccurate)
• superficially (with a temporal artery thermometer — this is a device which you wipe across your child's forehead to get a reading).

Oral temperatures
It's hard to take an oral temperature in children under five because they may not be able to cooperate. If your child has a blocked nose due to a cold, they may find it hard to breathe with their mouth closed. To take an oral temperature, wait five minutes after the child has had a hot or cold drink (or it will affect the temperature) then place the thermometer well under one side of the tongue. Have the child hold it in place with their lips, not their teeth, and tell them to breathe through their nose. Wait until the thermometer 'beeps' before taking a reading. Oral readings can be around half a degree lower than body temperature.

You can also use pacifier thermometers;these are good if your child already uses a pacifier. Infants or toddlers who do not use pacifiers generally may resist a pacifier thermometer, so something else might be easier to use.

Rectal temperatures
Rectal thermometers are better used for babies and young children under the age of 12 months than for older children, who will probably protest loudly. Rectal readings are most reliable for babies under the age of three months. Taking a rectal temperature is often difficult, especially when the baby is very active — the thermometer can slide out of the rectum, or the tip of the thermometer might damage the lining of the rectum. Place the tip of a digital thermometer just inside the anus, and wait for it to 'beep' before taking a reading.

Armpit temperatures
Under the armpit is usually the safest, but least accurate way to take a temperature, especially in young children. Place the thermometer in the armpit and close the arm, holding the elbow against the body. Wait for the thermometer to 'beep' before taking a reading. Armpit readings may record a temperature up to 1 degree lower than the actual body temperature.

Ear thermometers (infrared tympanic thermometers)
These are quick and easy to use. Your doctor or nurse can show you how to place the thermometer in the ear canal, so you get a reasonably accurate reading. A plastic cover is placed over the tip of the thermometer, which is held gently just inside the child's ear canal, until the thermometer 'beeps'. It is accurate to within about a degree, as long as the ear canal does not have a large plug of wax in it.

Temporal artery thermometers
These are relatively new, and are the simplest to use. The thermometer is scanned across the child's forehead. It has the advantage of allowing you to check a sleeping child, without waking them.

Several other methods have been introduced in recent years and are being marketed aggressively to parents. One method involves a plastic strip which is placed on the child's forehead and gives a digital reading of the temperature. However, this system is not very accurate. At best it can only provide a rough guide as to the child's temperature.

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