Why Does Body Temperature Rise In Fever?

Fever, or pyrexia, is when body temperature rises above the normal limit. It is the body’s defense mechanism, and most of the population will get a fever at some point in their lives. In this article, we will explain why body temperature rises in fever.

There are many causes of fever. It is often associated with pathogens that swell in the body and are recognized by the body as foreign particles.

This, of course, makes you wonder why body temperature rises in fever at all. It may seem detrimental at first, as any symptoms associated with an abnormal rise in body temperature will only increase the malaise caused by the foreign microorganism in question.

However, fever has an evolutionary significance, as do all physiological reactions in the human body. In today’s article, we discuss how necessary fever is for our survival and why body temperature rises in fever.

Relationship between fever and fever

As a rule of thumb, body temperature above 37 degrees means fever or heat. It can be divided into four types:

• Mild fever or heat is when the body temperature does not exceed 38 degrees Celsius.
• Moderate fever occurs when the body temperature is between 38 and 39 degrees Celsius.
• In high fever,  body temperature is over 39 degrees Celsius.
• Then there is still hyperpyrexia, i.e. a very high fever with a body temperature of 40 degrees Celsius or more.

Hyperpyrexia quickly presents with complications:  it can lead to denaturation of nervous system proteins,  with numerous disorders and a high risk of death if medical treatment is not obtained immediately.

Why does body temperature rise in fever?

Fever is a reaction of the body to external factors and is harmful to us when it is very high. Why then does the body raise its temperature if it can once be harmful?

First, fever should be thought of as a defense mechanism. The hypothalamus, the part of the brain responsible for regulating body temperature, sends a message to raise heat when it recognizes molecules in the blood known as pyrogens.

Pyrogens are any factors that cause fever: they can be, for example, polysaccharides or residues or products of bacterial cell walls. 

The immune system, which causes inflammation, reacts to defend itself against intruders. In this way, fever is one of the body’s defense mechanisms.

The body’s internal system “hopes” that by raising body temperature, the microorganisms most sensitive to temperature changes would die at higher temperatures. Most bacteria and viruses that cause infections do well at 37.5 degrees Celsius.

When the temperature rises sufficiently, the microorganisms stop multiplying, or at least they do not do so as quickly and efficiently. This makes them more fragile in front of the cells of the immune system. Fever is thus an evolutionary mechanism with a clear purpose: to attenuate pathogens.

Is fever an unnecessary or useful mechanism?

Fever thus helps fight disease, but it can also lead to death or cause irreversible damage in severe clinical conditions. This raises the following question: should doctors allow body temperature to rise? And if so, to what point?

This is a topical issue in medical circles. Some doctors would preferably maintain a moderate fever so that the immune system responds better to the pathogens, while some prefer to reduce it with antipyretics. There is no unanimous answer to this. However, all physicians agree that fever above 39 degrees requires immediate treatment.

For this reason, there are over-the-counter medications such as aspirin and paracetamol that lower body temperature. As modern medicine has also provided us with antibiotics and antiviral drugs, there is no longer a need for a sharp rise in body temperature to fight disease.

High body temperature is a reason to see a doctor

Fever is one of the body’s defense mechanisms that is triggered to eradicate potential pathogens. It not only kills microorganisms that are very sensitive to temperature fluctuations, but also weakens the most persistent of them.

For parents, an increase in a child’s body temperature is often a concern. However, they should understand the difference between a mild fever that may not exceed 38 degrees and a fever above 39 degrees.

In any case, fever is always a reason to go to the doctor. Call or go to the office if you notice an increase in your body temperature so that your doctor can diagnose the ailment early and prescribe appropriate treatment.