Is a common medical symptom and a sign characterized by an elevation of body temperature above normal. Temperature (98.6F) was established as Normal in 1868, but this has been muddled since (Jama 268: 1578-78, 1992).

Body temperature can increase after 30 minutes of activity or exercise, anxiety and even when you start getting excited and 1 hour after food. Sexual excitement (blushing) also increases your body temperature, breathing and heart rate.

The lowest temperature is usually recorded at around 3am, the highest at 6 pm.

Core (Rectal) temperature is used to assess for deviation from the normal range that may indicate disease, deterioration in condition, infection or reaction to treatment.

Doctors are still not sure nor do they have any special technique to differentiate bacterial from viral infections based on temperature. This is not a symptom that can be used to diagnose or treat but used in combination of other symptoms to help diagnose or treat illness.

Infection is one of the causes that is associated with fever. Fever is considered to be beneficial because it reduce nutrients and stop bacteria multiplying. Moderate fever also accelerates immune response and so helps us kill the bacteria.

Temperatures of our body must be within normal limits to help body metabolic functions to occur. Its like you trying to bake a cake in fridge.

The average normal body temperature taken in the mouth is 37ºC (98.6ºF), but anywhere between 36.5ºC and 37.2ºC (97.7ºF and 99ºF) may be normal.

Normal armpit temperatures are 0.2ºC to 0.3ºC lower than this.

A temperature of 38ºC (100.4ºF) or above is usually considered to be a significant fever – you should measure it again after two to three hours.

Antibiotics are NOT used to control or reduce body temperature but kill bacteria that release chemicals (pyrogen) that control our body temperature

Prescribing antibiotics not knowing the cause of infection is not safe because this drug can kill helpful bacteria living in our body and encourage colonization of antibiotic resistant bacteria.

What causes it?

Fever is caused by the release of certain chemicals in our body.

In the last few years, was surprised to hear doctors telling patients they have signs of inflammation and so must take antibiotics. This is not what pathologist or good clinicians would advice. Even the advice offered by so called experts and information published in the Internet is very confusing.  I think it would be better if I explain you the simple difference between Infection and Inflammation.

Inflammation can be defined as “The body response to an insult”. Bacterial or viral infection is ONE of the million causes that produce inflammation. This is a response to protect our body and is not harmful. The only problem we experience is “Pain”. Even pain is helpful because you get to know something is not right and you will first look at the part or take action to help reduce pain.

Blushing (red cheek) which makes you look attractive when you get excited, embarrassed, angry, post exercise, throat of a child after excessive crying, excessive rubbing of skin or when you touch hot pan are all inflammations that happened due to insult.

How the symptoms and signs of inflammation help us:

When you first experience sudden onset of local pain on your skin your hand moves spontaneously (reflex action) to touch the area. You may feel a small bump, area which is hot and experience more pain if you press hard. At times you may see an insect sitting on your skin and sucking out blood. If the area of pain is in your back or part that you cannot see, you may use a mirror or ask ask some one to take a look.

You may notice a reddish, swollen painful area that is hot to touch and realize you have been bitten by some insect.

Suppose the insect happens to be a mosquito, you call this “Mosquito bite”. The bitten area which is red, hot and painful is what we call “Inflammation” and not Malaria.

You may suffer from malaria only few days later and not soon after a mosquito bite. Malaria also occur only if the germs (Plasmodium) were introduced into your blood by a infected female mosquito. If the mosquito was male and not a carrier of the malaria germs, then the chances of you getting malaria is very low. Doctors do not prescribe malaria treatment just because you were bitten by a mosquito and have locally inflamed area.

You will be advised to take drugs to help prevent malaria germs entering your body when a  mosquito bites you when you travel to malaria infected area or country.

Abusing Antibiotics

Doctors working in the community, primary care often prescribed antibiotics saying the throat, ear or skin looks read and inflamed. Is this necessary?

The main reason they dish out prescription is to help protect themselves. In the past few years, patients were awarded huge compensation payment because they did not prescribe antibiotics early. This made doctors prescribe antibiotics even though they were sure you were suffering from viral infection. When doctors like me questioned doctors sid they were prescribing to help prevent secondry infection.

It is true, your immunity is reduced after viral infection and the chances of getting bacterial infection is high. This is one of the reason I always say you must not visit hospitals or clinics when you are suffering from acute viral infections because the chances of getting secondary bacterial infection is high.

The other problem you will encounter is about abusing antibiotics. No doctor will be able to say not to take antibiotics (fear of getting wrong and impending threat of litigations). After the doctors prescribe antibiotics, no patient will have the courage not to take it.

In the past, I have also prescribed antibiotics knowing the infection is viral. In the last few years, I started giving prescription and advice patients to wait for 2-3 days before getting them from the chemist knowing this was not necessary. This was because the patients were consulting my colleagues or visiting local walk-in-clincs and getting the antibiotics they expected.

The most important reason I gave the printed prescription was to make sure the patient does not return to sugery in the next 48 hours saying the fever has not settled and d demanding antibiotics. This is to help prevent them getting secondary infections.

My Anotation:

Un-invited guest (virus) enters your house (body) to help themselves and multiply. Once the babies are born (baby viruses) leave your house (body) and go out to infect others (this is called viral shedding). The viral shedding is said to increase when your body temperature is very high. Becasue the babies of un-invited guests (viruses) move out rapidly they forget to close the door of your house (body eg., skin and mucus membrane of throat, nose, connective, skin genitalia and intestines).

There are always strange people (bacteria) walking around in front of your house (body) will quickly enter your house (body) and create havoc. Bacterias do not know how to open the door and enter but once they enter they cause havock and often kill. Infections like meningitis, septicaemia or pneumonia are often secondary infections.

Prescribing Antibiotics:

Now we know it is not a good idea to prescribe antibiotics because these drug rapidly kill good germs and the resistant strain colonise and stay in your body up to eight weeks. The doctors and nurses also have tendency to prescribe low dose. This is more harmful than not taking any antibiotics.

It was very easy to prescribe antibiotics and get you out from the room as fast as possible but we failed to realise this conditioning actually undermine your confidence. We have made you believe you need antibiotics to cure your fever.

The body temperature is slightly high in most serious bacterial infections because of chemicals released by the immune system to help kill the germs.

Antibiotics DO NOT Reduce Temperature.

High temperature is said to be protective response and not a disease. High temperature in our body can actually kill some germs (REF) and so some doctors (including me) say we must not give drugs (paracetamol or anti-inflammatory) , to reduce body temperature. I prescribed paracetamol for children to help reduce pain and not temperature. These chemicals are safe but they do have some effect our body in the long term. As doctors we must “Do No Harm” and so think and justify this treatment is essential before prescribing.

Some sixty years ago (before Penicillin was invented 1940), many bacterial infections were fatal and fever was greatly feared. This was the only sign that doctors associated with infection. Simple Staphylococcus skin infection caused after a thorn prick or open wound killed thousands of people. The well known Flu Epedemic in USA in 1918, killed millions due to secondry Staphylococcus infection. (REF)

In 1940s, Doctors in UK were advertising in local shops and magazine and advicing people to consult them saying they may develop pneumonia if they start coughing. (REF)

These days there are effective treatments for most infections. Even so, fever is an important sign that someone is ill and a cause should always be established.

Other causes include any condition where there’s inflammation, from arthritis to trauma to inflammatory bowel disease.

Rare tropical haemorrhagic fevers include ebola, a highly infectious virus that rapidly breaks down the walls of arteries so the victim haemorrhages to death. It’s fatal in 90 per cent of cases.

Such fevers are extremely rare, but there’s a real risk of feverish infections such as malaria if you travel abroad, so seek advice before you travel.

When a doctor can’t find the cause of a persistent fever it’s called a fever of unknown origin (FUO, or PUO for ‘pyrexia of unknown origin’). Special tests may be needed to pinpoint the cause and detect hidden abscesses or unusual infections.

About 25 per cent of FUOs aren’t because of infection, so other explanations must be sought – most importantly cancer. About one in five people with chronic persistent fever has a tumour. People with lymphoma, lung, pancreatic or primary liver cancer often have fever caused by dead cancer cells or bleeding.

What’s the treatment?

Not every fever needs medical attention, but in young children, if the temperature continues to rise and fall (chills and rigours) or if there are other worrying symptoms, please  talk to your doctor. No doctors will criticise you for calling and speaking to them.

Rushing to consult is annoying to doctors and also can result in your child or you getting secondary infection. The worst thing to do is to rush to consult a doctor knowing your child has chicken pox (because you have heard from other mothers about chicken pox infection in the community or school. Why am I saying this? its because people who are immune-suppressed or on cancer treatment may die if they get chickenpox.

There are several things you can do to help bring the temperature down and make the person more comfortable:

  • Keep the room at a comfortable temperature, but make sure fresh air is circulating
  • Ensure they drink plenty of water, flat coke to prevent dehydration
  • Give ice cubes to suck an make sure the mouth is moist
  • Take off excessive layers of clothing – small babies or children may be left in a thin vest
  • Give a bath or shower using LUKE WARM water

Give medication regularly once every four to six hourly. Either paracetamol as tablets (adults) or syrup (children); ibuprofen as tablets (adults) or syrup (children);

Most parents I have come across check temperature regularly (once every 4 or 6 hour) or when they think the body feels warm and then give the drugs. This is not a sensible way to treat because drugs do not act as soon as you swallow and need good blood level to control temperature. Most parents told me that the temperature goes down after treatment but bounces back. It is true the temperature will fluctuate on and off until the virus leaves the body. Bacteria do not like temperature to go high and so will release a toxin that shutoff the body thermostat and so we see patients and children with serious bacterial infections (Meningitis, pneumonia, nephritis, appendicitis and septiciemia) all feel cold and in shock (blood vessels collapse to help reduce heat loss from body) and so called “Septic Shock”

If the child has difficulty to swallow, you can also give rectal suppositories.

Aspirin, for adults only. Children under 16 should not be given aspirin.

When to contact a doctor

Fever is rarely harmful, but at very high temperatures it can cause problems. For example, some small children with a high fever will have a seizure, known as a febrile convulsion.

A high fever may also be a sign of serious illness. Call your doctor and ask if you’re are worried, especially if:

  • If the behaviour changes occur
  • You or the child is feeling hot and cold or develop chills and rigours.
  • You suspect an infection, which might need antibiotic treatment
  • It’s in a very young child
  • The child becomes unusually sleepy or doesn’t respond
  • The fever is higher than 38.5ºC (101.3ºF)
  • The child won’t take fluids
  • Feels hot and cold

Fever in Guideline-1

Some doctors claim monitoring temperature is the best method used to diagnose infections. This is not true because body temperature is often low in serious infections and so monitoring temperature is no a good indicator of severity.

Most of these illness that produce very high temperature  (measles, mumps, rubella, chicken pox, typhoid, malaria and TB) are now not so common in western world. The way they were diagnosed in the past was based on temperature chart and is now not used.

In 1980, we insisted on regular hourly to six hourly TPR. This was not because the chart was necessary for us to mange the child but only make sure the child admitted in hospital was regularly monitored (the nurse will see the child 3-4 times in the night).

This regular monitoring was stopped because some nurses tried to find out if regular TPR is necessary. Based statistics, this practice was stopped saying “There is no evidence to prove regular TPR help mange patients”. The result of this is obvious – patients and children die at night un noticed.


Rapidity in which the temperature increase will result in fits not very high temperature. Very high temperature may make you or the child behave odd, speak some thing irrelevant or talk to themselves. The best treatment to do is to give a bath / shower with luke warm water (not cold water) and never use fan or aircooler to cool them down (this may precipitate a fit)

Parent / patients have a tendency to give antipyretics only after they find the temperature is high. It would be better if antibiotic was given on a regular basis (4 times / day). Drugs have to be absorbed and circulated in the body before they start working. If you give paracetamol after you notice high temperature, this will generally take few hours to start working and when the drug effect wear off temperature will spike again. You need to give the correct dose to make it work, so please check the Childs requirement, adults will need 1 gram every 6 hours

Some Illness & High Temperature

Malaria – They were named after their temperature charts. Tertiary (once in 3 days), Quaternary (once in 4 days.

Typhoid (Salmonella): Temperature increase but the pulse rate goes down (Reflex Bradycardia)

Measles: Rapidly increased high spiking temperature (often resulted in fits), then the temperature settled for 2 – 3 days, later we saw rash on the skin and the temperature went high again for 3-4 days.

Rubella: Similar to measles but they had milder form and a lymph node was swollen being the neck

Mumps: High temperature spikes, facial swelling in front and below ears

Chicken pox: High temperature with chicken pox spots often with sore mouth, eyes and genitalia.

TB: Temperature was slightly high in the evenings and was associated with sweating. More than 20% of TB are now resistant to treatment and is said to be rapidly spreading in Asia & Far East.

Bacterial Abscess: Spiking temperatures (feeling hot & cold) but will have localised abscess. If the abscess is internal (often in patients staying in hospitals and have had penetrating injury. This may become a common feature in the future if patient develops MRSA abscess.

7 thoughts on “Fever

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