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Understanding Fever

by Dr. Mandar V. Bichu
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Fever is the commonest symptom which promptly sends the patients and parents running to a doctor. It is the most over-rated, over-treated and mistreated symptom. So here is an effort to clear the myths and misconceptions regarding it.

What is fever?

In human beings the body temperature usually remains around 37*C (98.6*F) with a normal variation of 1*C above or below. Even normally the body temperature is low early in the mornings and goes up slightly late in afternoons. A core temperature of 38*C (100.4*F) or more usually is considered as ‘Fever’.

FEVER BY ITSELF IS NOT A DISEASE. It is just a reaction to an underlying illness.

How does it occur?

Hypothalamus – a small part in the brain- acts like a thermostat in maintaining the body temperature within the normal range. All the illnesses causing fever do so by prompting release of ‘pyrogens’ from various cells in the body. These ‘pyrogens’ are the fever-producing chemicals which reach the hypothalamus through blood stream and raise its set-point leading to fever.

Why does the patient feel cold shivers just before the appearance of fever?

It is because the hypothalamus thermostat set-point is already set higher and the rest of the body which is still at a lower temperature feels cold compared to the higher set-point.

What are the causes of fever?

Though theoretically there are several causes of fever, the most important cause in any age-group is Infections. So the most common cases of fever in daily life are due to infections caused by the viruses or bacteria.

Inflammatory disorders, immunity problems, malignancies, drugs and malingering (Factitious fever) are some other important causes to be considered in specific situations.

Remember – always think about the common things first! Don’t panic by assuming the worst possible cause.

How to check the temperature?

  1. The simplest way of roughly estimating fever is through touching the forehead of the patient by the back of your hand. Depending on the relative warmth of the patient’s skin, you can judge whether it is mild, moderate or high fever. This is the subjective assessment of fever which is not accurate but will give you an initial idea about the presence and severity of fever.

  2. To have the accurate and objective temperature assessment, one should always keep a thermometer handy at home.

  3. The traditionally used and fairly accurate mercury thermometer is nowadays not recommended for use in small children as it can break and has a risk of accidental mercury ingestion.
  • The electronic thermometers are simple to use. When the electronic thermometer detects correct temperature, it indicates immediately by giving a beep or lighting up.

  • The aural (ear) thermometers – the ones to be inserted in the ear canal – though touted as easy and quick, are sometimes difficult to use correctly in the smaller children and could give false readings in children with small angulated ear-canals or with ear-wax.

  • Temperature/thermometer strips are easy to use but their results are not that accurate.
  • Arm-pit (Axilla), mouth and rectum are the usual places to check the temperature.
  • Depending on the site of temperature check-up, we may need to do some adjustments to know the core or actual temperature.  A simple guideline is as follows:

Core temperature = Rectal temperature = Oral temperature + 0.5* C = Axillary temperature + 1*C 

(This means that we need to add 1*C to Axillary temperature and 0.5* C to Oral temperature to get the core temperature, which is almost equivalent to Rectal temperature).

  • The ideal time to keep the mercury thermometer is around 1 minute for rectal, 2 minutes for oral and 4 minutes for axillary temperature. But practically a 1 minute-recording gives a fair idea of the fever. In case of electronic thermometer, we get a beep when it detects the correct temperature.

Is fever risky?

In most commonly encountered situations, fever is not risky and indeed might be considered beneficial to aid the body defense mechanisms to get rid of the germs. If the child remains active, smiling and playful in spite of fever, then the outcome is most likely to be normal.

When is immediate medical attention needed in a case of fever?

In following situations, one needs to immediately seek medical attention.

  • Age less than 6 months
  • Sick look
  • Lethargy
  • Severe associated symptoms and signs
  • Hyper-pyrexia (>41*C)
  • Fever with chills and rigors
  • Continuous fever
  • Rapidly swinging fever with wide temperature fluctuations
  • Prolonged fever
  • Presence of serious pre-existing disease (cardiac, pulmonary, neurological or metabolic)

What about febrile fits?

Febrile fits usually occur at the beginning of fever during the sudden rise of temperature so there is no sense in worrying about them when the fever has already been there for some time. Moreover these fits are practically harmless and have no long-term medical consequences despite their frightful appearance. They can occur in almost 4% of normal children between 6 months- 6 years.

How do we treat fever?

  1. Medicines:

  2. Paracetamol (Acetaminophen) is the safest medicine for fever and in proper dose can be used four to six hourly. There are multiple formulations of this medicine (drops, syrup, suspension and suppositories) which have different strengths. The doses of these formulations should always be checked up with the doctor, rather than just relying on the label information. Overdose can lead to liver toxicity and under-dosing results in inadequate response.
  • People wrongly believe that suppositories are more effective than oral medicines in treatment of fever. The only situation where suppositories are useful is when the child is refusing to take any medicine orally or is vomiting.
  • Ibuprofen should be used only sparingly and under doctor’s supervision. It can have drawbacks like damaging stomach lining, causing kidney damage and triggering asthma attacks.
  • Aspirin is one medicine you should avoid in children as an anti-pyretic, especially in presence of viral illnesses like influenza or chicken-pox, as it can cause Reye’s syndrome – a serious liver affection.

  • Diclofenac, Mefenamic acid and Nimesulide are too strong anti-inflammatory agents, which are not really safe to use for the treatment of fever. Their usage is usually as a result of parental anxiety, medical overzealousness and a needless fear about fever.
  • Tepid Sponging
  1. Bath or sponging with tepid or lukewarm water is another method to bring down the temperature especially when the temperature is very high or is not coming down with medicine.
  • Don’t ever use cold water or ice-bag for sponging. It is not the temperature of the water that is going to bring the body temperature down. It is the heat of the body used to evaporate the water from its surface which will finally bring the core temperature down. And believe me, a cold water bath isn’t such a pleasant experience especially if you are having fever!
  • With a cloth made wet with lukewarm water, wipe the whole surface of the body. Keep the film of water on the body surface for a few seconds and then dry it. Keep doing the same cycle for 20-30 minutes.
  • If the child is not cooperating, give a quick lukewarm shower or make him sit in a tub filled with lukewarm water and then dry him.  It will also serve the same purpose as that of sponging.
  • Keeping a cologne water-soaked cloth over forehead may be an age-old popular method but it is not much effective to bring down the temperature.
  • Do not use alcohol/ spirit to rub the body or to add to the sponging water. It can cause toxicity.

Why do we treat fever?

It is only to prevent the associated aches, pains and misery. Some experts do believe in not treating a well looking child without a risk factor up to temperatures as high as 40*C.

Aren’t antibiotics necessary to treat fever?

If the cause of the fever is not a bacterial infection, antibiotics will not help one bit in treating fever. Almost 90-95% of common infections are viral. The common wisdom of not starting any specific treatment for first three days of fever is that most of the simple, common viral illnesses causing fever start subsiding by that time.

Does the height of fever give any indication of the severity of the underlying illness?

It is very difficult to differentiate a relatively harmless illness from a severe illness just from the height of the fever. In the earlier years of life even common cold can give rise to high-grade fever. So rather than just looking at the temperature value displayed on the thermometer, we should look at the patient as a whole. If his overall appearance and activity looks alright, then the chances of a common, uncomplicated illness are more!

Unfortunately this is the thing most of us forget to do and often end up making a mountain out of a molehill!

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