Fever is a syndrome, that is, a set of symptoms and signs that are caused by the body’s response to agents that are infectious in nature, although it can also occur as a reaction to toxins, injuries, etc. High fever in children occurs in 3 levels, the first is 37.2°C in the axillary area, 37.5°C in the oral area and 38°C in the rectal area. High fever in adults occurs in a temperature greater than 38 degrees throughout the body.

what is fever

As mentioned before, fever or hyperthermia is an alteration in the body temperature of people, as a means of reaction before unknown agents with harmful natures for the organism.

The temperature of the human body can change according to different factors, for example, in females, it tends to rise during their menstruation cycle, but, generally, it can also rise according to the physical activities that are carried out, the emotions strengths that they possess, the diet that they are carrying out, medications that are consumed regularly, the temperature of the environment and the humidity.

Due to the fact that most viruses and bacteria generate infections in the human body and that, in addition, they can survive in temperatures of 37 degrees, fever is considered a fundamental part of the defenses of the human anatomy to act against it. of these agents, so its presence in the body means that it is fighting for the patient, not against him.

Hyperthermia does not tend to cause brain damage unless it is a fever that exceeds 42 degrees. This happens when no treatments are used for the infection, but they rarely go above 40 degrees.

There are cases of febrile seizures, but that only happens in some children. Most of these high temperatures are eradicated, furthermore, it does not mean that, due to the seizure, the child or the person suffers from epileptic seizures. Seizures do not cause permanent damage and do not usually recur. There are also some hyperthermias that continue for days or weeks, these are unexplained and of unknown origin.

Fever symptoms

Doctors establish that, to realize that you actually have a fever, you must present some symptoms or signs, among them, are the following:


This is one of the main signs of hyperthermia. It is the increase in body temperature above the normal index (from 35 to 37 degrees). This is caused by an infection or inflammation. Although this is a common symptom and in fact the main one, there are times when it does not appear, but it gives rise to other signs that do become present in the body.

respiratory disorders

The respiratory rate tends to increase at the same time as the temperature, making the person feel totally agitated or tired.

digestive disorders

Appetite decreases and stomach secretion is minimal, which is why constipation is generated. All this causes thirst to increase and the patient tends to drink large amounts of water per day.

circulatory disorders

As with breathing, the pulse tends to increase in conjunction with temperature, this means that there are between 10 and 15 beats per minute. If the pulse is strong, it is a dynamic fever, if the pulse is weak, then it is adynamic fever. When there is no increase in pulsations in conjunction with the increase in temperature, then there is a dissociated fever.

Blood pressure

Here, the blood pressure tends to increase because an acute attack of fever breaks out, however, when the temperature is stabilized, the tension can normalize or remain in a subnormal state.

If the core temperature rises rapidly, then peripheral vasoconstriction is present, that is, the patient feels cold and has body tremors (chills). Now, if the temperature drops, there is peripheral vasodilation, that is, the patient is hot and seeks to find himself in cool places, there is sweat and muscle flaccidity.

fever levels

Fever - Fever Levels

Fever can occur at various levels, hence the state of the body and the seriousness of the matter are disclosed. In this section, the 3 common levels of fever will be explained: low-grade fever, fever, and hyperpyrexia.

low-grade fever

It is a slight fever or fever as it is also known. When a person has a body temperature above 37°C, but below 38°C, they are said to have low-grade fever, that is, they have hyperthermia that could be classified as mild or mild.

In general, low-grade fever appears as the body’s response to certain agents that cause some type of disease. It is common for these to be infectious pathologies caused by a virus or bacteria, but it can also reflect a deficiency in the immune system.

The truth is that this little fever should not last more than 24 hours, so it is advisable to be vigilant. Children are the most likely to have a low-grade fever, even more so at the stage where the first teeth begin to appear, but it also occurs when they have a cold or mild pneumonia. According to specialists, children tend to suffer from low-grade fever because their immune system is not yet fully developed.

Some of the symptoms that occur when having a low-grade fever are: headache, sweating, great thirst, reddened and hot skin, extremities (upper and lower) tend to get cold, increased heart rate and glassy eyes.

In these cases, doctors recommend taking antipyretics such as ibuprofen and Paracetamol, in addition to drinking plenty of fluids, taking baths with lukewarm water, wearing light clothes, and avoiding physical exertion. In addition, it is best to stay in bed until be fine

It is important to highlight (especially in cases of low-grade fever in children) that this is a very common condition in childhood, so parents are recommended not to be alarmed, if they are new parents, seek help from their pediatrician and This will tell you what treatment to give the little ones.


As has been mentioned throughout this content, it is about the progressive increase in temperature, from 37.2 degrees in the morning to 37.7 degrees in the afternoon. It is produced by the presence of infectious or toxic agents, the symptoms usually vary according to the patient. In children, fevers are usually normal and only last a couple of hours, maximum two days. There are several types, for example: yellow fever, rheumatic fever and typhoid fever.


It is a situation in which there is an increase in temperature above 41 degrees, this is the maximum temperature that the human body supports, if it continues to rise, then it can have serious brain consequences.

Consequences of fever

fever - Consequences

In general, high temperature is not usually dangerous because it acts to defend the body from agents of an infectious nature that can survive in the human anatomy, however, there are some cases in which hyperthermia can be dangerous.

For example, it is often dangerous in people who have lung and heart disease, this is because fever increases both heart rate and respiratory rate.

It is also possible that people have mental consequences due to poor management of the fever, and may develop dementia.

High temperatures can cause dysfunction or a serious problem in the organs of the human anatomy. The increase in temperature can be caused by a serious infection, be it malaria, meningitis or septicemia, which destroys the body’s organs and the nervous system in parallel.

Treatment for fever

To lower the fever, it is necessary to follow all the recommendations that the doctors send. Precisely for this reason, it is advisable to visit the patient’s trusted doctor and take the medicine for fever that he prescribes.

However, they can continue with home treatment fever to lower the temperature a little and return to a healthy state.

One of the easiest ways to lower a fever is to take a bath with warm water and stay under the water for a considerable time.

Another effective method is to apply cold compresses to your forehead and neck to feel cool and bring your body temperature back to normal. The main recommendations of the doctors is that people who have a high temperature do not wrap up too much, that will only make the temperature continue to rise and go from hyperthermia to low-grade fever or, in the worst case, to hyperpyrexia.

It is not advisable to self-medicate, as was said before, the best thing to do in these cases is to visit the doctor and rule out any possible disease or disorder that is causing the fever.

Frequently Asked Questions about Fever

At what temperature is a fever in adults?

From what is fever in children?

From 36 to 37.7 degrees.

What to do when a person has a fever?

Visit the doctor and follow all his recommendations.

How to lower a fever in a baby?

Following the recommendations of your pediatrician or, failing that, placing cold compresses on your forehead and neck.

How to know if a person has a fever?

Paying attention to the symptoms and taking their temperature in the axillary, rectal or oral areas.