Fever

What is fever

Fever is a raising of the body temperature, usually by the immune system in response to some type of infection.

Most bacteria that infect the body exist very comfortably at body temperature and by increasing body temperature to a higher level, the body is able to kill the bacteria or viruses by the millions and reduce or stop infection.

The body’s thermostat in the hypothalamus controls body temperature and fever.

Normal body temperature is about 37° C (or 98.6° F). Fever occurs when the body temperature rises above this.

Facts about fever

• Normal body temperature is about 37° C (or 98.6° F)
• Fever is a self defence mechanism controlled by the hypothalamus and initiating an immune system response
• Always err on the side of caution with children who have a fever over 40° C and take them to the doctor immediately (or call an ambulance – 000)
• If a child is convulsing due to fever and it does not stop after 5 minutes, call an ambulance – 000
• Children under 3 months who have a fever over 38° C (100.4°F) should be taken to a doctor immediately as they may be quite ill and require immediate medical attention
• Babies less than 6 weeks old who have any type of fever should be taken to a doctor as they require immediate medical attention
• Antibiotics have no effect on fever caused by viruses or any other reason other than a fever caused by a bacteria
• Aspirin should not be used in babies, children or teenagers to treat fever

Symptoms of fever

Fever generally causes the following symptoms:

• Alternatively feeling hot and cold
• Feeling generally unwell
• High body temperature (over 37.5° C)
• Hot feeling in the face
• Lethargy
• Shivering

High fever symptoms

If fever progresses or gets too high, it can cause the following symptoms:

• Confusion
• Fits (or convulsions) especially in babies and young children
• Hallucinations
• Muscle spasms
• Rapid heart beat (palpitations)

High fever can cause convulsions and may be especially dangerous in babies, toddlers, young children and the elderly if it is not reduced back to normal.

Always consult a doctor if fever is higher than 37°C or 98.6°F, especially if a baby or young child has a high fever.

Causes of fever

Fever is usually cause by the body in response to a viral or bacterial infection of some type. When bacteria or viruses invade the body and cause infection, they are able to do so because the body provides the perfect environment for them to multiply and infect. The body’s core temperature of 37°C (or 98.6°F) is the optimal environment for viruses or bacteria to live and breed, but they cannot survive long in temperatures a lot higher or a lot lower than this.

In response to a viral or bacterial infection, the hypothalamus (the body’s thermostat) increases the body temperature rapidly and drops it just as rapidly. This is why the symptoms of feeling hot then shivering cold are common symptoms of fever. The rapid changes in body temperature kills off many of the viruses or bacteria and prevents them from continuing to multiple. By rapidly increasing and decreasing the body temperature, the hypothalamus is trying to bring the body back to a healthy state.

Other causes of fever

• Chronic illness – these conditions can normally cause a recurrence of a low grade fever. The chronic conditions most likely to cause some fever are: rheumatoid arthritis, hay fever, bronchitis, sinusitis
• Heat stroke – can cause the body to heat up, but without any sweating usually, so that it feels like a fever
• HIV infection – one of the first sign of infection by the human immunodeficiency virus (HIV) is a low grade fever
• Leukaemia – the condition leukemia usually cause some type of recurrent fever
• Malignancies – some malignant tumours can cause fever to occur
• Tropical diseases – certain tropical diseases such as typhoid fever, can cause a fever, which can then recur over time

Prevention of fever

Non-preventable risk factors

Fever may be unpreventable in certain circumstances:

• Chronic health conditions – there are a number of chronic health conditions, which, while generally not serious, can cause a low grade fever every time they occur. A low grade fever is one in which the body temperature is slightly raised above normal. The conditions that most commonly cause a low grade fever are:
  • bronchitis
  • hay fever (allergic rhinitis)
  • rheumatoid arthritis
  • sinusitis
• Infection – if the body has been invaded by viruses or bacteria and an infection ensues, the hypothalamus may try to increase body temperature rapidly to make it less hospitable for the viruses or bacteria to continue to multiply
• Malignancy – Certain conditions such as leukaemia and malignant tumours can cause a fever (which can be one-off at the start of the condition or it can be recurrent). Fever can be the body’s response to the malignancy

Preventable risk factors

There really is no way to prevent a fever from occurring (as it is a self defence mechanism by the body in response to infection), but there are ways to reduce it:

• Cool compress – a cool compress can be made by wetting a face cloth and wringing it out and then placing this on the body pulse points (inner wrists, arms, neck, forehead and legs) to reduce body temperature naturally
• Keep hydrated – it is really important to keep the body hydrated when an infection of any type is present. Usually when a person has a fever, they tend not to feel very hungry, but liquids can be tolerated. Try to have as much of the following: water, diluted fruit juice and herbal teas (chamomile, peppermint and rose hip)

Complications of fever

Very high fever that is sudden or which has occurred over a prolonged period can be dangerous and cause serious complications, ranging from brain damage to death.

It can be dangerous when the body temperature increases too high or for too long, when the hypothalamus tries harder to get rid of the viruses or bacteria, as this can overheat the body.

Any type of fever (higher than normal body temperature and associated with infection) in newborn babies and infants should not be permitted to rise too quickly. The hypothalamus does not work as effectively in babies and infants as it does in older children and adults and high fever can become uncontrollable. If fever in a baby or infant reaches 42°C (106°F) brain damage can occur.

Always seek immediate medical attention if your baby or infant has a high temperature. This can have serious repercussions if not reduced back to normal.

When to see a doctor about fever

Babies and infants are the most vulnerable to the effects of high fever as their body temperature can rise very quickly during an infection.

General guidelines on fever for babies, infants and children

• Babies that are less than six weeks and have any type of fever may develop an uncontrolled fever (due to their inability to reduce fever) and require immediate medical attention
• Infants under 3 months who have a fever over 38° C (100.4°F) should be taken to a doctor immediately as they may be quite ill and require immediate medical attention
• Children that are convulsing for over five minutes, due to a fever may need urgent medical attention – take them to the doctor immediately (or call an ambulance – 000)
• Always err on the side of caution with children who have a fever over 40°C (104°F) and take them to the doctor immediately (or call an ambulance – 000)

General guidelines on fever for adults

• Adults who have a fever over 40°C (104°F) need to seek immediate medical attention
• Adults with a low grade fever associated with a chronic medical condition (such as rheumatoid arthritis, hay fever, bronchitis, sinusitis) need to seek medical attention as this indicates there is an infection which needs to be diagnosed and treated
• Adults with persistent fever not associated with any chronic medical condition need to seek the advice of a medical practitioner to determine the cause of the fever

Diagnosis of fever

Fever is diagnosed by the following:

• Medical history – the doctor will ask a series of questions about the duration and onset of fever, whether or not you have measured it and will ask about other symptoms
• Physical examination – the doctor will examine the eyes, ears and throat to check for infection, as well as the skin (if necessary). The doctor will also check the body temperature with a thermometer (either under the armpit, in the mouth, in the ear or rarely in the rectum)

Today thermometers are mostly electronic so a diagnosis of temperature can usually be taken fairly quickly.

It is highly recommended for parents to keep a thermometer at home, in order to check and monitor their children’s body temperature when they have an infection.

Today, electronic thermometers can be purchased from a chemist. They provide a very quick and accurate diagnosis of temperature, so it can be easily monitored.

An electronic thermometer is a valuable part of a first aid kit.

Nurses at Australian hospitals take a patients’ temperature by gently moving their highly sensitive electronic thermometer around the perimeter of the patient’s face, generally not even touching the person’s face.

Conventional treatment of fever

The conventional treatment of fever (especially if it is caused by a viral or bacterial infection) recommends the following:

• Cool compress – it is advisable to use a cool compress, which is a cloth that has been moistened through with cold water and then dabbed on the pulse points of the skin to cool the body down and reduce the fever. Once the cloth warms up (and it will do so quickly), it is time to moisten it again with cold water and apply it again. This should be repeated until the body temperature has been reduced (take a measurement with a thermometer after apply the cool compress). It is a treatment especially recommended for babies and children, as it helps reduce their fever considerably in many cases
• Increase fluid intake – it is recommended to drink more water and fruit juice to help rehydrate the body and in doing so, help lower body temperature. Babies and children with fever should be given diluted juices
• Monitor temperature – it is important to monitor body temperature to ensure the fever has reduces and temperature steadily falls back to normal, but if it continues to increase, seek medical attention. In babies and children with fever, their temperature must be regularly monitored as they are more vulnerable to the effects of increased body temperature. Use a digital (or electronic) thermometer, as it is more precise and does not contain any toxic mercury
• Paracetemol or ibuprofen – the function of these medications is to work on lowering body temperature and reducing fever. These are the only medications that should be used for reducing fever, especially in babies and children. Do not use aspirin in babies and children to treat fever
• Rest – the doctor will recommend that you have plenty of rest to help your body heal from the infection and lower the fever. Try to keep babies and children cool enough so that they can sleep comfortably

Alternative / complementary treatment of fever

There are a number of alternative/complementary treatments recommended for fever:

Herbs

There are a number of excellent herbs which may help to provide relief for symptoms:

• Elderflower tea – studies show that the flowers of the elderberry tree have significant anti-viral and anti-bacterial properties. Elderberry tea helps to lower the levels of the virus or bacteria, which in turn will help to lower fever
• Garlic – the herb garlic should be incorporated either as a supplement or fresh in food, to assist the body in healing when fever is caused by a bacterial or viral infection. Garlic has excellent anti-bacterial and anti-viral properties and can help to reduce likelihood of infection in the first place

Vitamins

There are a number of vitamins which may help to provide relief for symptoms:

• Vitamin A – the potent antioxidant vitamin A assists the body to heal more quickly, especially when the fever is due to a bacterial or viral infection and this is because vitamin A helps to boost the immune system to fight off the infection more effectively. Vitamin A is best if taken prior to infection, to prevent it from getting worse, but can be taken when infection is present too to reduce fever
• Vitamin C – the potent antioxidant vitamin C especially help the body to reduce fever and is especially effective if taken in the powdered form (which is generally less acidic). Vitamin C has anti-viral properties, which help to reduce levels of virus and this helps to reduce fever

Minerals

There are a no minerals which are recommended to treat fever.

Other nutrients

There are a no other nutrients which are recommended to treat fever.

Dietary modifications

There are a number of dietary modification strategies which may help to provide relief for symptoms:

• Increase fluid intake – drink plenty of plain water (around 8-10 glasses), juices (mix them with water) and herbal tea such as peppermint and chamomile to help replace the fluids lost through the fever, to help the body rehydrate and help with healing

Lifestyle modifications

There are a number of lifestyle modifications which may help to provide relief for symptoms:

• Cold compresses – use a wet cotton cloth on the pulse points (forehead, chest and arms especially, but also legs) to help lower the body temperature. The cold compress should be re-applied every 10-15 minutes as the cloth will heat up quickly due to the high body temperature
• Rest – resting the body and sleeping more, without exertion allows the body to heal itself naturally. The body is usually fighting an infection when fever is present and resting gives the body more resources to help with the healing process

Alternative treatments

There are no other alternative treatments recommended to treat fever.

Always ensure that you notify your medical practitioner of any supplements that you want to take – it may interfere with other medication or conditions you have. Confirm with your doctor it is safe to take before you try it.

Living with fever

Self care strategies

There are some general recommendations for managing fever at home:

• Cool compress – use a wet cotton cloth on the pulse points (forehead, chest and arms especially, but also legs and torso) to help lower the body temperature. The cold compress should be re-applied every 10-15 minutes as the cloth will heat up quickly due to the high body temperature
• Increase fluids – ensure that you (or your child) are drinking adequate amounts of water, diluted fruit juice and herbal teas such as peppermint and chamomile. These types of fluids help to hydrate the body and reduce likelihood of dehydration
• Medical attention – if fever increases to over 38° C (100.4°F) in children or over 40°C (104°F) in adults then you need to seek medical attention. When to see a doctor has the recommendations for fever for babies, infants and children. Always seek immediate medical attention for babies under six weeks who have any type of fever
• Monitor temperature – if babies, infants or children have a fever, they need to be regularly monitored to ensure the fever does not rise too high. Children with infection can have a very quickly rising fever, so monitoring is vital to prevent complications due to fever. Adults with a low grade fever should monitor it to ensure it does not rise too high
• Paracetemol or ibuprofen – a doctor or other medical practitioner will recommend paracetemol or ibuprofen to reduce body temperature and fever
• Rest – it is really important to rest, either by sleeping or laying down and staying stationary, to give the body the best chance of reducing the number of viruses or bacteria, reducing infection and therefore reducing fever

Caring for someone with fever

Partner

If you have a partner with a fever, there are some useful strategies that can assist them:

• Monitor temperature – use a thermometer to monitor your partner’s temperature at regular intervals and seek medical attention if it rises above 40°C (104°F)
• Use a cool compress – use a wet cotton cloth on the pulse points (forehead, chest and arms especially, but also legs and torso) to help lower the body temperature. The cold compress should be re-applied every 10-15 minutes as the cloth will heat up quickly due to the high body temperature

Friends

If you have a friend with a fever, there are some useful strategies that can assist them:

• Medical attention – seek medical attention for your friend if their temperature rises above 40°C (104°F)

Parents

If you have a child with a fever, there are some useful strategies that can assist them:

• Increase fluids – ensure that your child is drinking adequate amounts of water, diluted fruit juice and herbal teas such as peppermint and chamomile. These types of fluids help to hydrate the body and reduce likelihood of dehydration
• Monitor temperature – use a thermometer to monitor your child’s temperature at regular intervals and seek medical attention if it rises above 38° C (100.4°F) in children, above 38° C (100.4°F) in infants younger than three months and any fever in babies less than six weeks
• Use a cool compress – use a wet cotton cloth on the pulse points (forehead, chest and arms especially, but also legs and torso) to help lower the body temperature. The cold compress should be re-applied every 10-15 minutes as the cloth will heat up quickly due to the high body temperature

References

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• Murray M, Pizzorno J. Encyclopedia of Natural Medicine, 2nd Edition. Prima Publishing USA 2000.
• Osiecki H. The Physicans Handbook of Clininical Nutrition, 6th Edition. Bioconcepts Publishing QLD, 2001
• Schmitt BD. Your Child’s Health: The Parents’ One-Stop Reference Guide to: Symptoms, Emergencies, Common Illnesses, Behavior Problems, and Healthy Development., 2nd Edition. Bantam Publishing, USA 2005
• Tratter R, Jones A. Better Health Through Natural Healing: How to Get Well Without Drugs or Surgery, 2nd Edition. McGraw Hill, 2001
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Last reviewed and updated: 5 May 2025