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At what body temperature is it dangerous: Fever – Myths Versus Facts

Fever – Myths Versus Facts

Many parents have false beliefs (myths) about fever. They think fever will hurt their child. They worry and lose sleep when their child has a fever. This is called fever phobia. In fact, fevers are harmless and often helpful. Let these facts help you better understand fever.

MYTH. My child feels warm, so she has a fever.

FACT. Children can feel warm for a many reasons. Examples are playing hard, crying, getting out of a warm bed or hot weather. They are “giving off heat.” Their skin temperature should return to normal in about 20 minutes. About 80% of children who act sick and feel warm do have a fever. If you want to be sure, take the temperature. These are the cutoffs for fever using different types of thermometers:

  • Rectal (bottom), ear or forehead temperature: 100.4° F (38.0° C) or higher
  • Oral (mouth) temperature: 100° F (37.8° C) or higher
  • Under the arm (Armpit) temperature: 99° F (37. 2° C) or higher

MYTH. All fevers are bad for children.

FACT. Fevers turn on the body’s immune system. They help the body fight infection. Normal fevers between 100° and 104° F (37.8° – 40° C) are good for sick children.

MYTH. Fevers above 104° F (40° C) are dangerous. They can cause brain damage.

FACT. Fevers with infections don’t cause brain damage. Only temperatures above 108° F (42° C) can cause brain damage. It’s very rare for the body temperature to climb this high. It only happens if the air temperature is very high. An example is a child left in a closed car during hot weather.

MYTH. Anyone can have a seizure triggered by fever.

FACT. Only 4% of children can have a seizure with fever.

MYTH. Seizures with fever are harmful.

FACT. These seizures are scary to watch, but they stop within 5 minutes. They don’t cause any permanent harm. They don’t increase the risk for speech delays, learning problems, or seizures without fever.

MYTH. All fevers need to be treated with fever medicine.

FACT. Fevers only need to be treated if they cause discomfort (makes your child feel bad). Most fevers don’t cause discomfort until they go above 102° or 103° F (39° or 39.5° C).

MYTH. Without treatment, fevers will keep going higher.

FACT. Wrong, because the brain knows when the body is too hot. Most fevers from infection don’t go above 103° or 104° F (39.5°- 40° C). They rarely go to 105° or 106° F (40.6° or 41.1° C). While these are “high” fevers, they also are harmless ones.

MYTH. With treatment, fevers should come down to normal.

FACT. With treatment, most fevers come down 2° or 3° F (1° or 1.5° C).

MYTH. If you can’t “break the fever”, the cause is serious.

FACT. Fevers that don’t come down to normal can be caused by viruses or bacteria. The response to fever medicines tells us nothing about the cause of the infection.

MYTH. Once the fever comes down with medicines, it should stay down.

FACT. It’s normal for fevers with most viral infections to last for 2 or 3 days. When the fever medicine wears off, the fever will come back. It may need to be treated again. The fever will go away and not return once the body overpowers the virus. Most often, this is day 3 or 4.

MYTH. If the fever is high, the cause is serious.

FACT. If the fever is high, the cause may or may not be serious. If your child looks very sick, the cause is more likely to be serious.

MYTH. The exact number of the temperature is very important.

FACT. How your child looks and acts is what’s important. The exact temperature number is not.

MYTH. Oral temperatures between 98.7° and 100° F (37.1° to 37.8° C) are low-grade fevers.

FACT. These temperatures are normal. The body’s normal temperature changes throughout the day. It peaks in the late afternoon and evening. A true low-grade fever is 100° F to 102° F (37.8° – 39° C) .

SUMMARY. Keep in mind that fever is fighting off your child’s infection. Fever is one of the good guys.

If your child’s illness or injury is life-threatening, call 911.

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Last Reviewed: 07/22/2023

Last Revised: 12/30/2022

Copyright 2000-2023 Schmitt Pediatric Guidelines LLC.

Fever – Better Health Channel

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Read the full fact sheet

  • Fever is a rise in body temperature, usually caused by infection.
  • Fevers caused by viral illnesses shouldn’t be treated with antibiotics, since these drugs have no effect against viruses.
  • High fever (about 41.5°C or more) is extremely dangerous and could trigger convulsions.
  • Seek medical attention if you are concerned, particularly about fever in a child.

About fever

Fever is a rise in body temperature above the normal temperature, usually caused by infection. Normal body temperature is around 37°C (give or take a degree, but this can vary from person to person). There may also be minor fluctuations over the course of the day and night.

The fever triggered by a viral or bacterial infection is caused by chemicals produced by the immune system, which reset the body’s thermostat to a higher level.

Contrary to popular belief, the severity of fever isn’t necessarily related to the seriousness of the illness – for example, life-threatening meningitis might only cause a small temperature rise.

Most cases of mild fever resolve by themselves within a couple of days. A mild fever (up to 39°C) can actually help the immune system to get rid of an infection. In children between the ages of 6 months and 6 years, fever can trigger convulsions. A fever of 42.4°C or higher, particularly in the elderly, can permanently damage the brain.

Symptoms of fever

The symptoms of fever can include:

  • feeling unwell
  • feeling hot and sweaty
  • shivering or shaking
  • chattering teeth
  • flushed face.

Infection is usually the cause of fever

The cause of fever is usually an infection of some kind. This could include:

  • diseases caused by viruses – such as colds, flu, COVID-19External Link or other upper respiratory tract infections
  • diseases caused by bacteria – such as tonsillitis, pneumonia or urinary tract infections
  • some chronic illnesses – such as rheumatoid arthritis and ulcerative colitis can cause fevers that last for longer periods
  • some tropical diseases – such as malaria, which can cause bouts of recurring fever or typhoid fever
  • heat stroke – which includes fever (without sweating) as one of its symptoms
  • drugs – some people may be susceptible to fever as a side effect of particular drugs.

Self-treatment suggestions for fever

Suggestions to treat fever include:

  • Take paracetamol or ibuprofen in appropriate doses to help bring your temperature down.
  • Drink plenty of fluids, particularly water.
  • Avoid alcohol, tea and coffee as these drinks can cause slight dehydration.
  • Sponge exposed skin with tepid water. To boost the cooling effect of evaporation, you could try standing in front of a fan.
  • Avoid taking cold baths or showers. Skin reacts to the cold by constricting its blood vessels, which will trap body heat. The cold may also cause shivering, which can generate more heat.
  • Make sure you have plenty of rest, including bed rest.

When to see your doctor for fever symptoms

You should always consult with your doctor in the following cases:

  • You are still feverish after 3 days, despite home treatment.
  • Your temperature is over 40°C.
  • You are shivering and shaking involuntarily, or your teeth are chattering.
  • You seem to be getting sicker as time goes by.
  • You have unusual symptoms such as hallucinations, vomiting, neck stiffness, skin rash, rapid heart rate, chills or muscle spasms.
  • You feel confused and drowsy.
  • You have a severe headache that doesn’t respond to painkillers.
  • You have recently travelled overseas.

When to seek immediate urgent medical attention

You should seek immediate medical attention if you or someone else has the following symptoms:

  • fever with headache and a stiff neck
  • rash that does not blanche to skin pressure (indicates bleeding into the skin) – this can be a sign of a life-threatening illness.

Diagnosis methods

Since fever is a symptom and not an illness, the underlying cause must be found before specific treatment can begin. Some tests may be necessary if the cause of the fever is not clear after your doctor has taken a medical history and performed an examination. These tests may include:

  • blood tests
  • urine examination and culture
  • throat swabs or mucus sample examination and culture
  • stool examination and culture
  • x-rays.

Treatment options

Treatment depends on the cause – for example, chronic tonsillitis may require surgery to remove the tonsils (tonsillectomy).

Fevers caused by viral illnesses shouldn’t be treated with antibiotics, since these drugs have no effect against viruses. In cases of mild bacterial infection, it is usually best to allow your immune system to handle the problem, rather than take antibiotics.

Fever in children

On average, a child has up to 10 infections per year.

Body temperature isn’t a reliable indicator of illness for babies and young children – a child may have a mild temperature according to the thermometer (slightly over 37°C), but seem happy and healthy.

See a doctor right away if your child:

  • is aged six months or less
  • has a rash
  • has a fever of 40°C or more
  • is still feverish after a day or so, despite 4-hourly doses of baby paracetamol
  • vomits or has persistent diarrhoea
  • refuses food or drink
  • cries inconsolably
  • seems listless, floppy or just looks ill
  • convulses or twitches
  • has trouble breathing
  • is in pain.

If you feel at all worried or concerned at any stage, consult with your doctor.

Using a thermometer

If you suspect that your child has a fever, you can use a thermometer to measure their temperature. Remember, though, that body temperature is better used as a guide than a reliable indicator of illness for babies and young children – a child might have a mild temperature according to the thermometer (slightly over 37°C), but may seem happy and healthy.

There are several types of reliable thermometers available, which come with instructions on how to use them. They are available from a chemist. If you are in doubt about which one to choose for your child, or have questions about how to use it, ask your pharmacist to explain.

Treatment for fever in children

  • Dress your child in light clothing.
  • Give drinks of clear fluid (like water).
  • Keep your child cool.
  • Give paracetamol in the correct dose for the child’s age (but not more than 4 doses in a 24-hour period). Do not give regular paracetamol medicine for more than 24 hours without seeking advice from your doctor.
  • See your doctor if your child is 3 months or younger.
  • Don’t give your child a cold bath.

Fever can cause convulsions

A febrile convulsion is a fit or seizure that occurs in babies and children when they have a high fever, usually from an ear infection or a viral upper respiratory infection. The fit can last a few seconds or up to 15 minutes, and is followed by drowsiness.

Approximately 3% of otherwise healthy children will have one or more febrile convulsions between the ages of 6 months and 6 years. A febrile convulsion is not epilepsy and does not cause brain damage. There is no way to predict who will be affected or when this will happen.

The symptoms of febrile convulsion include:

  • loss of consciousness (black out) – the child will fall if standing and may pass urine
  • twitching or jerking of arms and legs
  • breathing difficulty
  • foaming at the mouth
  • going pale or bluish in skin colour
  • eye rolling, so only the whites of their eyes are visible
  • your child may take 15 minutes to wake up properly afterwards – they may be irritable and appear not to recognise you.

Convulsions are rarely serious. If your child has a convulsion you should:

  • Try to stay calm and don’t panic.
  • Place your child on the floor and remove any objects they could knock against.
  • Don’t force anything into your child’s mouth.
  • Don’t shake, slap or try to restrain your child.
  • Once the convulsion has stopped, roll your child onto their side, also known as the recovery position. If there is food in their mouth, turn their head to the side, and do not try to remove it.
  • Note what time the fit started and stopped, so you can tell the doctor.
  • Have your child checked by your local doctor or nearest hospital emergency department as soon as possible after the fit stops to find the cause of the fever.
  • Call triple zero (000) for an ambulance if the fit lasts more than 5 minutes.

Where to get help

  • In an emergency, always call triple zero (000)
  • Emergency department of your nearest hospital
  • Your GP (doctor)
  • Maternal and Child Health Line Tel. 13 22 29(24 hours, 7 days)
  • NURSE-ON-CALL Tel. 1300 606 024 – for expert health information and advice (24 hours, 7 days)
  • Pharmacist

  • Fever in childrenExternal Link, The Royal Children’s Hospital Melbourne.
  • Febrile seizuresExternal Link, The Royal Children’s Hospital Melbourne.
  • Fever – febrile convulsionsExternal Link, The Sydney Children’s Hospitals Network.

This page has been produced in consultation with and approved

Department of Health – Public Health – Communicable Disease Prevention and Control

This page has been produced in consultation with and approved

Department of Health – Public Health – Communicable Disease Prevention and Control

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Content on this website is provided for information purposes only. Information about a therapy, service, product or treatment does not in any way endorse or support such therapy, service, product or treatment and is not intended to replace advice from your doctor or other registered health professional. The information and materials contained on this website are not intended to constitute a comprehensive guide concerning all aspects of the therapy, product or treatment described on the website. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions and to ascertain whether the particular therapy, service, product or treatment described on the website is suitable in their circumstances. The State of Victoria and the Department of Health shall not bear any liability for reliance by any user on the materials contained on this website.

Reviewed on: 21-06-2022

Fever ✅ Information for Patients from Experts Sanmedekspert

Fever in a child or adult is always a serious cause for concern. Why it appears when you need to urgently see a doctor, and when you don’t need to knock it down, how to properly reduce it at home – these and many other questions are answered by experienced specialists of our clinic.

The most optimal temperature for biochemical processes in the human body is from 36.5 to 37.2°C. If the thermometer shows deviations of 1 – 1.5 ° C up or down, then it means that the body has failed. An elevated temperature is called up to 39°С, and high – from 39°С.

Types of temperature:

  • Norm – from 35°С to 37°С. This indicator directly depends on many factors: time of measurement, gender, age of the person.
  • In case of hyperthermia, the temperature is above 37°C. This condition is due to a violation of the mechanisms of thermoregulation: an excess of heat from outside or, conversely, difficult heat transfer. For example, clothes that are too warm, heat stroke, sunstroke, burns, physical activity, etc.
  • Fever (fever) is a protective reaction of the body to the appearance of foreign agents in it:
  1. fungal infection,
  2. viruses,
  3. bacteria,
  4. pathological process – for example, damage to the nervous system, hemorrhage, inflammation, trauma, etc.

In fever, thermoregulatory mechanisms are preserved. There are mild fever (38 – 38.5 ° C), moderate (38.6 – 39.5 ° C) and high (above 39.5 ° C). Temperatures above 40.5 – 41°C are a serious danger to life.

Causes of fever

  • Colds.
  • Viral and bacterial infections.
  • Rheumatism.
  • Inflammatory processes in the internal organs.
  • Eruption of milk teeth in children.
  • Overeating.
  • Physical overload.
  • Period before menses in women, etc.

Is it true that fever is good for you?

Light heat activates the body’s defenses. As soon as the “invasion of the enemy” occurs, all organs begin to release pyrogen proteins into the blood. They, in turn, trigger an increase in temperature and the production of antibodies and interferon protein, which kill harmful microorganisms. By artificially lowering the temperature with drugs, we interfere with the immune system to fight the infection.

It has been proven that at a temperature of 38 – 38.5°C the following processes occur in the body:

  • the production of antibodies to the pathogen and interferon increases;
  • significantly slows down the reproduction of viruses and bacteria;
  • the liver more effectively neutralizes toxic waste products of pathogenic microorganisms, and the kidneys excrete them faster with urine;
  • there is an increased activity of enzymes;
  • bactericidal properties of blood serum and lymph increase.

A slight fever, although unpleasant in its symptoms, helps to recover faster. By knocking it down, we expose ourselves to even greater danger. After taking an antipyretic, a person will, of course, feel much better, but an undefeated infection will remain inside, continue to spread quietly throughout the body and can provoke serious complications to the kidneys, such as pyelonephritis or cystitis.

How to help the body with a fever?

  • Do not raise the temperature artificially.

Do not take a hot bath, do not steam your feet, do not put mustard plasters and alcohol compresses, do not drink alcohol, hot milk, tea, coffee, do not wrap yourself in blankets.

  • Drink plenty of fluids.

Drink should be plentiful and warm, it can be at room temperature, and always unsweetened. Best of all – mineral water with lemon, lingonberry or cranberry juice. The blood becomes more liquid, toxic substances are excreted faster, the body does not suffer from dehydration. Sugary drinks are dangerous because water will come out with sweat, and glucose will become an additional food source for pathogens.

  • Sweat properly and stay in bed

Intense sweating is a natural thermoregulatory mechanism during fever. Evaporating from the skin, sweat cools the body and prevents it from overheating. Wrapping the patient in several blankets and insulated pajamas, we prevent the sweat from evaporating. A person with a fever should be dressed in cotton clothing and lie under a light, thin blanket. Linen should be changed as it gets wet.

  • Cleanliness and fresh air.

The room must be clean and well ventilated. As a rule, a sick person breathes through his mouth, which means that, together with moist, stale air, an infection will quickly penetrate into his lungs. The air temperature in the room should be approximately 22°C – 24°C. It is extremely important that there are no drafts.

  • Do not wipe your body with vodka or alcohol.

Alcohol vapors evaporate very quickly and cause severe hypothermia and severe chills. It is best to wipe the body with a sponge dipped in warm water, or put the patient in a cool bath for a while.

  • Food should be light

All fried, salty, fatty, spicy foods and alcohol should be excluded from the diet during illness. The best choice is low-fat broths, juices, fruit drinks, fresh and boiled fruits, vegetables.

How to bring down the temperature correctly and in what cases should it be done?

You need to start lowering the temperature if it is above 38-38. 5°C, lasts more than 3-5 days or the thermometer approaches 40°C. You can do this in the following ways:

  • the patient should drink plenty of warm, unsweetened liquids;
  • cold compresses applied to the forehead, neck, wrist, armpits and groin areas, as well as cool foot baths and wet sheet wraps, work well;
  • wiping should be done as follows: moisten a towel in warm water, first wipe your face with it, and then hands, body and legs;
  • A cooling bath will help reduce the temperature and flush out toxins. First, the patient is placed in a warm bath, then cold water is gradually added to it up to a temperature of 30 ° C;
  • Antibiotics can only be prescribed by a doctor. Before his arrival, you need to take antipyretics.

When do you need to urgently call an ambulance?

  • The thermometer shows above 39.5°C.
  • Fever is accompanied by abdominal pain (especially in the elderly and children), vomiting, weakness, limited movement, visual disturbances, or severe neck muscle tension (the person cannot tilt the chin to the chest).
  • Children under the age of 10 have a very dry, barking cough. In combination with temperature, this symptom indicates an inflammatory narrowing of the larynx (false croup).
  • If the temperature rises above 38°C very quickly, within 1-2 hours. This is especially dangerous if a child under 6 years of age is sick, and he has already experienced convulsions during heat – in this case, even a small temperature of 37.5 ° C is fraught with serious consequences.
  • Mild fever is dangerous for people with convulsive readiness and cardiovascular disease.

If fever is accompanied by weakness, pain in the joints and muscles, blurred vision, consciousness, headache, convulsions, shortness of breath, you should immediately consult a doctor. Also, be sure to make an appointment if you have a slightly elevated temperature for more than 7 days.

What body temperature is considered normal?

Body temperature is individual for each person and depends on different characteristics of the body, however, in some cases, a low or high temperature may indicate serious problems. This was told to Izvestiya by the head of the polyclinic department of the MEDSI Clinical Hospital No. 1 in Otradnoye, a therapist-oncologist Natalia Tolstykh.

According to the specialist, body temperature can be influenced by such indicators as metabolic characteristics, the work of the endocrine glands or the autonomic nervous system. At the same time, for each person during the day, the temperature fluctuates within small limits, remaining in the range from 35.5 to 37.2 degrees for a healthy person.

The temperature may also vary depending on the activity (with high activity, the temperature may rise slightly) and the time of day. Normal daily temperature fluctuations are 0.5–0.7 degrees. When a person falls asleep, all processes in the body slow down and the body temperature drops slightly, getting closer to 35-36 degrees, Tolstykh explained.

“It is important to understand that lower (compared to the population norm) body temperature, that is, less than 35. 5 degrees, may be an individual feature of some people, and does not always indicate the presence of diseases. Low body temperature, or the so-called hypothermia (below 35.2 degrees), can be caused by hypothermia, intoxication, problems with the endocrine system (reduced thyroid function – hypothyroidism, or adrenal insufficiency) “- said the oncologist.

Hypothermia also occurs in severe infections among the elderly, with hypothermia. Often the temperature can be lowered within a few days after a person has had an infection – the so-called asthenic trace.

“This is a signal that the body has coped with the infection, but is still weak and there is a risk of getting sick again,” the expert explained.

In addition, exposure to heat and cold, physical activity, consumption of spicy foods and/or heavy meals, and pregnancy (up to 37.4 degrees are common) can cause slight changes in temperature.

“37.1–38 degrees is the so-called subfebrile temperature. It may persist for up to two weeks after infection with fever. In the absence of other symptoms, this condition does not require additional examination and treatment. Quite often, colds occur in an erased form, and the detection of temperature is an accidental finding, ”added Tolstykh.

Speaking of elevated temperature, she emphasized that such a reaction of the body is its response to the introduction of a pathogenic microorganism. With good tolerance, fever up to 38.6 is better not to bring down the intake of antipyretics, since bacteria and viruses reproduce worse at elevated ambient temperatures, the doctor recommended, specifying that this concerns a healthy young body without concomitant pathology.

However, there are exceptions to this general rule. Body temperature should be treated more carefully in some cases.

“Firstly, in the pathology of the cardiovascular system (in particular, coronary heart disease, heart failure), an increase in temperature causes a high load on the heart, an increase in heart rate, therefore, in such cases, the temperature drop threshold can be reduced to 38 degrees. Secondly, with a non-infectious cause of fever (paraneoplastic, that is, tumor diseases, fever, fever in rheumatoid diseases), it makes no sense to withstand high temperatures, ”the specialist said.

According to Tolstoy, children usually tolerate temperatures up to 39 degrees, but the doctor noted that there are people who are sensitive to febrile convulsions, that is, their development when the body temperature rises.

Usually we are talking about a fever above 40 degrees, but convulsions individually can develop at a temperature of 39 degrees or even lower. In such cases, it is important to remember this feature of the child and prevent such an increase in temperature.

“At a temperature of 41 degrees and above, the protein begins to denature everywhere, in fact, the body is boiling – such a temperature is life-threatening,” the expert draws attention. In this case, the temperature must be lowered – antipyretics, cooling with a cold blanket and rubbing will help.