Fever: Causes, Effects and when to Treat it

The combination of holidays, extreme weather and returning to work is usually the perfect storm for brewing a cold. Suffering a cold with mucus, tiredness, and a fever is definitely annoying.

When these symptoms occur, people tend to prevent them with medication immediately. What we don’t realize is that these symptoms are our defense against viruses


Fever is the crucial and basic response to infection. For over 600 million years both warm and cold blooded vertebrates have had them.

In fact, even some plants react to an infection with an increase in temperature (study).

Do you think it’s a good idea that we’ve decided to block fever altogether with medication?

In today’s post we will learn how fever occurs, what happens when we have it, and when to use medication to get rid of it.

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What is Fever?

Fever is a body response that appears during an infection or an inflammatory disease.

Fever in warm-blooded animals comes at a high metabolic cost. A one degree increase in body temperature requires a 10 to 12.5% increase in basal metabolism. The body has to be very clear that you will benefit or it won’t invest so many resources.

There is evidence that the 1 to 4 degree increase in body temperature during fever improves our ability to recover and battle infections.

There is a correlation between the use of antipyretics (fever reducing drugs, like aspirin) and influenza related death. According to a study, people infected with a flu virus who took fever reducing drugs experienced a 5% increase in chances of death (study).

Although it’s true, a fever is not always beneficial. In cases of significant inflammation or sepsis, lowering the body’s temperature is the best way to treat this (study).

What happens when you have a Fever?

The induction and maintenance of a fever is a coordinated effort between the innate immune system, the peripheral and central nervous system.

First of all, the immune system detects some pathogen (bacteria, virus or fungus).

Once detected, it releases substances called cytokines. They inform our body that we have been infected.

Our brain perceives these signals and reacts. It produces neurotransmitters that increase our body temperature. The most studied substance with pyrogenic effects (increased body temperature) is Prostaglandin E2.

This substance is released both in the brain and in the affected tissues of the body.

To increase the temperature, the body stimulates the metabolic activity of brown adipose tissue. Vasoconstriction (constriction of blood vessels) of the limbs then reduces passive heat loss.  

The musculature also contributes to the increase of temperature. It uses its own energy deposits to produce heat.

How does fever function?

A fever is a complex process. It has an effect on the entire body. However, let’s look at the main functions:

  1. It stimulates the release of neutrophils from the bone marrow and promotes their recruitment to the site of infection. Neutrophils is critical in both infection recovery and in tissue repair.
  2. It increases the cytotoxic activity of cells called Natural Killers (NK). NK cells are also key in protecting against tumors.
  3. It increases the phagocytic capacity of macrophages and dendritic cells. This accelerates the elimination of pathogens and the cleaning of dead tissue. It also aids in the presentation of the pathogen to the rest of our defenses to achieve an optimal immune response.
  4. It improves the traffic of specialized cells, such as lymphocytes, to the infected area. Specialized cells help generate the most appropriate response depending on the pathogen encountered.
  5. It increases the permeability of blood vessels close to the infection, to allow all this trafficking of immune cells.
  6. At first, a fever stimulates production of inflammatory substances. Once the immune cells are active, there is a release of anti-inflammatory substances to achieve a modulated response. 

A fever helps to direct our defenses towards the place of infection. It also makes it more effective in eliminating the pathogens and resolving the damage caused by them.

For a proper immune response to an infection, our body depends on an increased body temperature.

Fever and Medication

Of course, there are always situations where we should resort to Antipyretics. The two most common situations are:

  1. The same substances that induce an increase in temperature provokes sick-like behavior. We will not feel like doing things, we will be uncomfortable, less motivated, tired and feeling down. This is because our immune system activates during a fever and our defenses consume more energy. During this process, we prefer to stay-at-home, saving energy for our defenses to use. When the discomfort is too high, we can resort to antipyretic remedies. Antipyretics improve feelings and sensations momentarily although they run the risk of delaying the infection recovery.
  2. As our body temperature increases, we rely on our metabolism. If the body is very weak, it may not tolerate such an aggressive response. So, in this situation, lowering the fever is recommended.

We recommend consulting your doctor before deciding whether to take medication or not.

Conclusion: Is fever a good thing?

Over millions of years, fever has remained a protective function. Essentially, the survival benefit it gives us is greater than the metabolic cost of increasing our body temperature. 

High temperatures related to fever serve as a systemic alert. It promotes the immune system during pathogen invasion. 

The understanding of the protective immune system has changed radically the way we approach fever.  Fever reacts as a defensive process so we should stimulate it rather than block it.

These learnings has opened up new ways to exploit immunostimulant activities, especially in therapies for cancer and autoimmune pathology.

Trust your body. It has 2 million years of experience in fighting infections.

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  1. Sum it up better please is fever good or bad yes or no simple or basically say what we do is bad because we just are lazy and think taking a pill will cure it just like we think about everything just throw a pill at it if it doesn’t work right doctors are stupid