How many degrees is considered fever? Know when to worry

Whenever we talk about diseases, we have symptoms that can indicate that the body has that disease.

fever is one of these symptoms are common to many diseases. It is nothing more than an increase in body temperature (in medical terms, it is called pyrexia).

When faced with this sign, it is common for a question to arise: after all, from how many degrees is fever considered?

How many degrees is considered fever?

It is considered fever when the body temperature reaches more than 37.6ºC, and the body temperature below this value is considered normal.

Above 39.6ºC it is considered a high fever stage or a febrile stage. In such cases, it is common for the person to have delusions or to lose consciousness.

If the thermometer number indicates more than 41 ° C, the person has hyperthermia. When this happens, the body collapses and there is a high chance of death or serious sequelae.

This relationship with the values ​​can be a little complicated, so the image below helps to better understand:

It is important to remember that fever is not a disease, but a way to combat something that is harming the body.

Thus, it is not necessarily a bad thing. In cases of infections, for example, it works as a defense mechanism of the body, helping it to get rid of the infectious agent.

It is also worth mentioning that the ideal temperature value can be changed according to the time of day.

For example, in the morning it is common for the temperature to be a little lower. During this period of the day, temperatures higher than 37.2º C already require attention.

At nightfall, the body temperature usually tends to be higher and, therefore, in these conditions the thermometer numbers should be of concern only if they exceed 37.7 ° C.

Our body temperature is controlled by the hypothalamus, a part of the brain that adjusts the temperature of internal organs.

The balance happens in the temperature happens through the loss of heat (between the skin contact and the external environment) or else the production of heat by the internal metabolism.

What is feverish state?

The feverish state is like a “pre-fever”. Its main characteristic is the body temperature: between 37.3 ° C and 37.7ºC.

But what does this mean in practice?

Well, when the person has this temperature, it is as if a warning light in the body was turned on.

From that moment on, it is important to be monitoring your body temperature frequently. You can also make warm compresses or ingest water, in an attempt to lower the numbers on the thermometer.

Keep in mind that something had to happen for the temperature to rise. The point is to try to find out what that factor was.

If the body is raising the temperature to fight an infectious agent, the person may experience symptoms such as headaches, cough and runny nose.

But there are other issues that can raise the temperature to a feverish state and are quite common, such as female ovulation or body movement during exercise.

But a tip to try to find out if it is serious or not is to observe if this feverish state is transient or not.

How to measure body temperature?

The safest way to measure the body’s internal temperature is with the help of a thermometer that can be either mercury or digital. To do this, just place the tip of this object under the armpit (axillary temperature), which is the most common way especially if done at home.

But, sometimes, it is not possible to determine an exact value of the axillary temperature. In such cases, it is also possible to measure the rectal temperature by gently inserting the thermometer into the anus – usually done in hospitals.

Even the thermometer inserted into the mouth, if used correctly, can measure the body’s internal temperature.

However, oral temperature is a little recommended practice since the saliva present in the mouth may end up decreasing the degrees indicated on the thermometer.

As these are different parts of the body, these temperatures also have different values ​​for what is considered or not a fever.

Thus, fever is considered when:

  • Axillary temperature higher than 37.5 ° C;
  • Rectal temperature is higher than 38 ° C;
  • Oral temperature is greater than 37.4 ° C.

When should the fever be worrying?

In general, fever should be worrying if it is accompanied by other symptoms such as headache , sore throat , vomiting, difficulty breathing, mental confusion, sensitivity to light (photophobia) or to sounds and tremors. In such cases, the ideal is always to seek medical advice.

Another sign that indicates that fever can be a complication is the time it lasts, even if compresses or medications are used.

In general, after taking some measure to lower the fever, the ideal is to wait between 30 and 40 minutes to measure the temperature again.

If the person spends hours with a high temperature, without decreasing over the period, it is better to go to the hospital.

In addition to time, it is also important to monitor the temperature: high fever (over 39.6ºC) requires medical supervision immediately, regardless of other circumstances.

What can cause fever?

Well, the fever is caused by the body itself. When the body is being threatened (by a virus or bacteria, for example) it raises the temperature in an attempt to eliminate this infectious agent and thus stay alive.

Now that this has been clarified, let’s go to the factors that can cause this reaction in the body:

  • Infectious agents: the presence of some virus and bacteria is an example of a situation that makes the body protect itself with the increase in temperature;
  • Medicines or drugs: these substances can cause side effects causing the temperature to rise;
  • Sun: sunburn and heat stroke (when the person is exposed to the sun for a long time) are other factors that tend to cause fever;
  • Dehydration: severe stages of this condition can cause fever. In these cases, the temperature rises due to lack of water, which helps to “cool” the cells and organs, maintaining their proper functioning;
  • Diseases: some inflammatory diseases (such as arthritis), immunological diseases (lupus) or tumors can also increase the numbers on the thermometer. 

Is high fever dangerous?

High fever is very dangerous mainly because it can cause mental confusion, shortness of breath, bleeding and changes in vital signs (acceleration of the heart, for example). In more extreme cases, the temperature above 39.6ºC can induce a state of coma.

Fainting, weak pulse and excessive sweating, causing dehydration are other dangers that high fever can bring.

In addition to these, it is also possible that high fever causes a stage known as a febrile seizure.

The main ones characterized by this generalized seizure are loss of consciousness, trembling in arms and legs on both sides of the body, upturned eyes, excessive salivation and breathing difficulties.

In most cases, it does not cause major damage and has a short duration, which varies between 10 and 15 minutes.

Children up to 5 years of age are the group most likely to be affected by febrile seizures.

40 degrees of fever can kill?

Sadly yes. The fever itself does not kill, but it can cause convulsions and heart attacks because the body has gone into a panic, as if it were “cooking” inside.

At this stage, the person is usually no longer conscious or lucid. It is normal for there to be moments of delusions and delusions.

After 40ºC, the person will probably also be dehydrated, since he will have eliminated all the water from the body through sweat.

The maximum temperature that a person can reach without harm to health is 42ºC. After that, there is no guarantee that it will remain alive, since its organs, cells and tissues will be damaged by the excess heat.

What temperature is considered a fever in a baby?

Well, babies’ bodies are not so different from adults. Thus, the temperature suitable for one is also suitable for another. Therefore, it can be said that babies over 37.5ºC have a fever. The difference between babies and adults is the way of caring during the situation.

Babies are more sensitive. Therefore, if the child under 3 months has a temperature above 38ºC, it should be evaluated by a pediatrician.

It is important to say that in the first year of life, it is common for the baby’s temperature to vary widely.

This is because the hypothalamus (the part of the brain that controls temperature) is not yet well developed in the little ones.

So, if the baby has plenty of covers, it is normal for his body temperature to rise rapidly.

But then how do you know when it’s really fever?

A tip is to take the child’s temperature after a bath with warm water. This tends to help regularize the numbers on the thermometer.

Also note if there are signs of irritation (crying and feeling unwell). If the baby is uncomfortable and the temperature is rising, go to the hospital for help.

What to do when the fever is high?

One of the most effective ways to lower your fever is to take anti-thermal remedies that should be prescribed by a doctor as per each case. These drugs help to reduce body temperature, but they should only be taken with medical advice, as they can cause adverse reactions or even mask the problem – which makes it difficult and delays the correct diagnosis.

Other tips include cold compresses on the torso and limbs, placing a damp towel on your forehead, or taking a bath with warm water.

Finally, rest and consume plenty of water are guidelines that can be followed when the body temperature is high, as they help to recover from the body.


Fever is a symptom that something is wrong in the body and therefore requires care and medical advice.

When the temperature is very high, the person may be at serious risk. So, when you suspect something and have doubts, try to visit a hospital as soon as possible

The newsroom of Hickey solution brings other information on health and the human body . Follow our posts.

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