What temperature is considered dangerous for a fever. How to distinguish between high and low grade fevers. What are the most effective methods to reduce a fever. When should you seek medical attention for a fever.

What Constitutes a Normal Body Temperature?

Body temperature can fluctuate throughout the day, typically being lowest in the morning and highest in the late afternoon. For children aged 2-18 years, normal temperature ranges are:

• Rectal temperature: 96.8°F to 100.3°F (average 98.6°F)
• Oral temperature: 95.8°F to 99.9°F (average 97.6°F)

Understanding these ranges is crucial for accurately identifying when a fever is present. But what exactly causes a fever?

Common Causes of Fevers

Fevers can be triggered by various factors, including:

• Illnesses (viral or bacterial)
• Vaccinations
• Overheating
• Certain medications

When the body detects an invader, such as a virus or bacteria, it raises its internal thermostat as a defense mechanism. This increase in temperature creates an environment less hospitable for pathogens, while simultaneously boosting the immune system’s efficiency.

Identifying High and Low Grade Fevers

Fevers are typically categorized as either low grade or high grade. But how do we distinguish between the two?

Low Grade Fever

A low grade fever is generally considered to be a temperature between 99°F and 100.9°F (37.2°C to 38.3°C). These fevers are usually not cause for concern and often resolve on their own.

High Grade Fever

A high grade fever is typically defined as a temperature of 103°F (39.4°C) or higher. For children between 2-18 years old, medical professionals often don’t become concerned until the fever reaches 104°F (40°C).

Is medication always necessary for fever reduction? Surprisingly, for children in this age range, medication may not be needed until the fever reaches 102-103°F (38.9-39.4°C), and only if the child is uncomfortable.

When Does a Fever Become Dangerous?

While fevers can be alarming, they’re rarely dangerous. However, certain situations warrant immediate medical attention.

Truly Dangerous Fever Temperatures

A fever becomes truly dangerous when it exceeds 108°F (42.2°C). Fortunately, such extreme temperatures are extremely rare and typically only occur in extraordinary circumstances, such as during a severe heat wave.

Any fever above 105°F (40.6°C) should be investigated by a medical professional. However, it’s reassuring to know that less than 1% of fevers ever reach this level.

When to Seek Medical Attention

While most fevers aren’t dangerous, certain symptoms accompanying a fever require immediate medical attention:

• Difficulty breathing
• Disorientation or confusion
• Seizures
• Stiff neck

Additionally, you should contact your pediatrician if:

• The temperature exceeds 104°F (40°C)
• The fever persists for more than 3 days
• Your child appears lethargic
• There are signs of dehydration (dry mouth, no tears, no urination for >8 hours)
• There’s burning or pain during urination
• The fever is accompanied by other concerning symptoms (ear pain, vomiting, diarrhea)

Effective Methods for Reducing a Fever

While it’s often best to let a fever run its course, there are times when reduction is necessary for comfort or safety. How can you effectively reduce a fever?

Non-Medicinal Approaches

Several non-medicinal approaches can help manage a fever:

• Rest: Encourage your child to get plenty of sleep, as this allows the body to focus its energy on fighting the infection.
• Hydration: Offer plenty of fluids to prevent dehydration and help regulate body temperature.
• Cool environment: Ensure your child isn’t overdressed or covered with too many blankets.
• Cool compress: Apply a lukewarm washcloth to the forehead, wrists, or back of the neck.

Medicinal Approaches

If medication is necessary, the two main options are acetaminophen (Tylenol) and ibuprofen. It’s important to note:

• Aspirin should never be given to children under 18 due to the risk of Reye’s syndrome.
• It’s preferable to stick with one medication rather than alternating between acetaminophen and ibuprofen.
• If the chosen medication doesn’t reduce the fever by 2-3°F within an hour, you may switch to the other option.

Always follow dosage instructions carefully to avoid accidental overdose.

The Role of Fever in the Immune Response

While fevers can be uncomfortable, they play a crucial role in the body’s defense against infection. How does a fever support the immune system?

Cytokine Production

When the body detects an invader, it produces chemicals called cytokines. These mediators help to reset the body’s thermostat, leading to an increase in temperature.

Enhanced Immune Cell Function

The increased body temperature creates an environment where immune cells, such as macrophages, can function more efficiently. These cells actively combat invading organisms.

Antibody Production

Fever stimulates the production of natural antibodies, which are crucial for fighting current infections and providing future immunity.

Given these benefits, it’s often best to let a low-grade fever run its course rather than immediately trying to reduce it.

Accurate Temperature Measurement Techniques

Accurate temperature measurement is crucial for proper fever management. What are the most reliable methods for different age groups?

For Children 2-4 Years Old

For toddlers, several methods are appropriate:

• Temporal artery temperature
• Ear (tympanic) temperature
• Rectal temperature (most accurate, but least comfortable)

Armpit (axillary) temperature is the least accurate and not recommended.

For Children 4 Years and Older

As children grow, more options become available:

• Oral temperature (once the child can hold the thermometer under their tongue)
• Temporal artery temperature
• Ear temperature

By this age, rectal temperatures should no longer be necessary.

Dispelling Common Fever Myths

Several misconceptions about fevers persist. Let’s address some of these myths to ensure better understanding and management of fevers.

Myth: All Fevers Are Contagious

Contrary to popular belief, not all fevers indicate a contagious condition. While viral infections that cause fevers are typically contagious, fevers can also result from non-contagious factors such as vaccinations or overheating.

Myth: Fevers Must Always Be “Broken”

Unless a child’s fever reaches 103°F (39.4°C) or higher, or the child is extremely uncomfortable, there’s often no need to actively “break” the fever. The fever itself is a sign that the body is fighting an infection.

Myth: Higher Fever Means More Serious Illness

The height of a fever doesn’t necessarily correlate with the severity of the illness. A mild infection might cause a high fever, while a more serious condition could result in a lower fever or no fever at all.

Myth: Fever Causes Brain Damage

Fevers caused by illness do not cause brain damage. Only temperatures above 108°F (42.2°C), which are extremely rare, pose this risk.

Understanding these facts can help alleviate unnecessary anxiety and promote more effective fever management.

Fevers – Toddlers and Teens (2-18 years)

You’re not alone – we all fear the dreaded fever. It’s typically the first sign that something is going on with our kiddo and we rush around, grabbing all the medicine, preparing for the worst. Let’s start instead by congratulating our love’s immune system for doing its job and see how this plays out.

Fevers are caused by:

• Illnesses (viral or bacterial)
• Vaccinations
• Overheating
• Certain medications
  ‍

What is a normal temperature for kids?

As a whole, our body temperature can range quite a bit throughout the day. It is lowest in the morning and highest in the late afternoon. A normal rectal temperature reading can range from 96.8℉ to 100.3℉ (average of 98.6℉). A normal oral temperature reading can range from 95.8℉ to 99.9℉ (average of 97.6℉).

When is a fever too high for a child?

For our kids who are 2-18 years old, we can let their fever hit 104℉ before we start to worry. You don’t even need to medicate them before they hit the 102-103℉ mark! If they are uncomfortable, you may give them Tylenol or ibuprofen, but otherwise it’s okay to let that fever get rid of the virus for them. No aspirin for any children under the age of 18. Keep your kiddo hydrated and make sure she’s not overdressed or lying in a pile of blankets.

It is a common misconception that we must rotate Tylenol and ibuprofen, but choosing just one is actually preferred. If the one you chose does not bring the fever down 2-3 ℉ within an hour, you may switch to the other medication. Our biggest concern is accidentally overdosing our kids – the less we give, the less we need to worry!

How to take temperature?

Two to four year olds: Temporal artery temperature, armpit (axillary) temperature, ear (tympanic) temperature, or rectal. If you’re ever questioning the results, rectal is the most accurate when in doubt. Axillary is the least accurate and not recommended.

Four years and beyond: All of the above will work for this age but hopefully by now, they can hold a thermometer under their tongue for an oral reading. Again, axillary is the least accurate. Rectal readings should be a distant memory for them now (and you, Mom and Dad!), thank the heavens.

Call your pediatrician if:

• Temperature goes higher than 104℉
• Any fever present more than 3 days
• Your kiddo is lethargic
• You notice signs of dehydration (dry mouth, no tears, no urinating >8 hrs)
• Burning or pain with urination
• Fever is accompanied by other symptoms that concern you (ear pain, vomiting, diarrhea)
  ‍

When to go to the ER with fever?

• Difficulty breathing
• Disoriented/confused
• Seizures
• Stiff neck
  ‍

When is a fever dangerous?

A truly dangerous fever is >108℉ and is extremely rare, only seen in situations such as a heat wave. However, all fevers >105℉ should be investigated with a doctor. That said, less than 1% of fevers go higher than 105℉.

How to break a fever?

Rest, drink lots of fluids, and stay cool! Remember: that fever is on our side, fighting off our infections. So unless our child’s fever hits 103℉ as discussed, there is no ‘breaking’ necessary.

Are fevers contagious?

Not necessarily. If a virus is the reason your child has a fever, then yes, they are considered contagious. But as discussed in the beginning here, vaccines or overdressing can also cause a fever – not contagious. And there are plenty of illnesses that may NOT cause a fever, so in general, don’t use fever as your guide on whether or not it can be spread to others.

Keep in mind that how your kiddo is behaving is always more important than the actual number on your Kinsa thermometer. Follow your gut if you feel like something is wrong, but otherwise don’t be afraid to let your kiddo’s immune system be the champion!

Fever | Boston Children’s Hospital

Your child has a fever if her temperature is 100.4 degrees Fahrenheit or higher.

The body has several ways to maintain normal body temperature. The body responds to changes in temperature by:

• increasing or decreasing sweat production
• moving blood away from, or closer to, the surface of the skin
• getting rid of, or holding on to, water in the body
• naturally wanting to seek a cooler or warmer environment

What causes a fever?

When your child has a fever, her body works the same way to control the temperature but it resets its thermostat at a higher temperature. The temperature increases for a number of reasons:

• Chemicals called cytokines or mediators are produced in the body in response to an invasion from a microorganism, malignancy, or other intruder.
• The body is making more macrophages, which are cells that go to combat when intruders are present in the body. These cells actually “eat up” the invading organism.
• The body is busily trying to produce natural antibodies which fight infection. These antibodies will recognize the infection next time it tries to invade.
• Many bacteria are enclosed in an overcoat-like membrane. When this membrane is disrupted or broken, the contents that escape can be toxic to the body and stimulate the brain to raise the temperature.

What conditions can cause a fever?

The following conditions can cause a fever:

• infectious diseases
• certain medications
• heat stroke
• blood transfusion
• disorders of the brain

What are the benefits of a fever?

A fever actually helps the body destroy its microbial invader. It also stimulates an inflammatory response, which sends all kinds of substances to the area of infection to protect the area, prevent the spread of the invader, and start the healing process.

What are the symptoms that my child may have a fever?

Children with fevers may become more uncomfortable as the temperature rises. The following are the most common symptoms of a fever. However, each child may experience symptoms differently. In addition to a body temperature greater than 100.4 degrees Fahrenheit, symptoms may include:

• Your child may not be as active or talkative as usual.
• She may seem fussier, less hungry, or thirstier.
• Your child may feel warm or hot. Remember that even if your child feels like she is “burning up,” the actual rectal or oral temperature may not be that high.

The symptoms of a fever may resemble other medical conditions. According to the American Academy of Pediatrics, if your child is younger that 2 months of age and has a rectal temperature of 100. 4 degrees Fahrenheit or higher, you should call your pediatrician. If you are unsure, always consult your child’s physician for a diagnosis.

When should a fever be treated?

If your child is very uncomfortable, treatment may be necessary. Treating your child’s fever will not help her body get rid of the infection any quicker, but it will relieve discomfort associated with it.

Rarely, children between the ages of 6 months and 5 years can develop seizures from high fever (called febrile seizures). If your child does have a febrile seizure, there is a chance that the seizure may occur again, but, usually, children outgrow the febrile seizures. A febrile seizure does not mean your child has epilepsy.

What can I do to decrease my child’s fever?

Give her an anti-fever medication, such as acetaminophen or ibuprofen. DO NOT give your child aspirin, as it has been linked to a serious, potentially fatal disease, called Reye syndrome.

Other ways to reduce a fever:

• Dress your child lightly. Excess clothing will trap body heat and cause her temperature to rise.
• Encourage your child to drink plenty of fluids.
• Give your child a lukewarm bath.
• Place cold washcloths over areas of the body where the blood vessels are close to the surface of the skin such as the forehead, wrists, and groin.

When should I call my child’s physician?

If your child’s temperature reaches 105 degrees Fahrenheit, this is considered a medical emergency and your child needs immediate medical attention, according to the American Academy of Pediatrics.

Call your child’s physician immediately if your child is younger than 3 months old and any of the following conditions are present:

• Your child’s rectal temperature is greater than 100.4 degrees Fahrenheit.
• Your child is crying inconsolably.
• Your child is difficult to awaken.
• Your child’s neck is stiff
• Purple spots are present on the skin.
• Breathing is difficult AND does not improve after you clear the nose.
• Your child is unable to swallow anything and is drooling saliva.
• Your child looks or acts very sick; if possible, check your child’s appearance one hour after your child has taken an appropriate dose of acetaminophen.

Call your child’s physician within 24 hours if your child, 3 months or older, has any of the following conditions present:

• The fever is 102 degrees Fahrenheit or higher (especially if your child is younger than 2 years old)
• Burning or pain occurs with urination
• Your child has had a fever for more than 24 hours without an obvious cause or location of infection.

Call your child’s physician during office hours if any of the following conditions are present:

• Your child has had a fever for more than 72 hours.
• The fever went away for more than 24 hours and then returned.
• Your child has a history of febrile seizures.
• You have other concerns or questions.

The temperature has risen.

What you need to know

37.0 — is this already a disease? When should you take an antipyretic? Can heat kill? Why is it advised to eat less at a temperature? We analyze popular questions

Usually we consider a fever a sign of SARS, influenza or other infectious disease. However, it can also jump after vaccination, although there is no infection in the body. Deviations from the temperature norm have dozens of reasons. To understand why this happens, it is worth learning more about the thermoregulation of our body.

In 1851, the German physician and scientist Karl Wunderlich summarized the results of a million temperature measurements in the armpits of patients and for the first time established the normal limit of 37°C, or 98.6°F. He also put into practice regular measurements of the temperature of patients and argued that fever (fever) is not the disease itself, but its symptom.

However, later studies revised Wunderlich’s estimate and reduced the rate to 36. 6°C. This was due not so much to the scientist’s mistakes as to the improvement in the quality of life. Wunderlich lived in an era when the average life expectancy was 38 years, and many people suffered from chronic infections such as tuberculosis, syphilis and periodontitis. A high level of systemic inflammation in the body could lead to such a norm.

At the same time, the temperature norm also depends on the place of measurement: in the armpit – it is 36.6 ° C, in the anus and vagina – 37.5 ° C; in the mouth – 37.0 ° C. By the way, the axillary method is considered the least accurate, but it has entered hospital practice as the simplest and most hygienic. For example, in the United States at home, a thermometer is placed in the mouth. But not any thermometer is suitable for this, you need a special one.

No. The temperature depends on daily biological cycles (at night and in the morning it is lower than during the day and in the evening), physical and mental activity, emotional state (fear, stress), and ambient temperature. Also, temperature regulation is disturbed by drug and alcohol intoxication. A constant temperature of 37.2 ° C can be in women during the period of ovulation and in pregnant women. Therefore, it is important to measure the temperature, if possible, in a calm, unexcited state.

Without illness or other physiological disturbances, the temperature will not exceed 37.2°C. But then begins what experts call subfebrile (from the Latin febris – fever) temperature – from 37.2 to 37.8 or even 38.0 ° C. Usually she speaks of a sluggish inflammatory process, that the body is fighting infections, and other disorders.

Subfebrile temperature can be distinguished by other signs of the disease – weakness, headache, sweating and body aches.

Yes, but not only. Subfebrile temperature can be observed in hundreds of different conditions. These can be various kinds of infections (for example, this is one of the symptoms of early tuberculosis), poisoning, dental diseases, allergic reactions, latent autoimmune diseases and chronic pathologies.

The temperature within these limits can also increase after receiving a dose of ionizing radiation of 2 to 4 Gy, against the background of hormonal changes in women during menopause. With prolonged or very acute stress, the body can also respond with an increase in temperature – this condition is called psychogenic fever, or thermoneurosis.

It is worth noting that such a temperature in itself does not harm the body. It is simply a tool the body uses to deal with real or imagined threats. For example, an increase in temperature after vaccination is considered a variant of the norm: the body thinks that it is being attacked, and just in case, it “alarms” all defenses.

Infectious agents such as viruses, bacteria and fungi do not live comfortably at certain temperatures. Let’s say 37.0 is already above the average annual temperature of any place on Earth, including the Sahara and the South American tropics. And the higher the column crawls, the worse it is for microorganisms. For example, biologist Arturo Casadevall studied the temperature preferences of 4,082 species of lower fungi. It turned out that less than a third survive at temperatures above 37°C, and only five percent grow at 41°C.

An increase in temperature is an element of non-specific (aimed at a wide range of threats) immunity. The hypothalamus, located at the base of the brain, is responsible for temperature regulation. It responds to signals from biochemical substances floating in the blood, called pyrogens (from other Greek πῦρ – “fire”). At elevated temperatures, metabolic processes are faster, and therefore the action of immune cells is accelerated.

Pyrogens are secreted mainly by cells of the immune system (monocytes, macrophages, T- and B-lymphocytes). When the hypothalamus detects them, it tells the body to generate and retain more heat, causing a fever. In children, the temperature usually rises faster because their immune system is still immature.

It should be said right away that mercury thermometers in Russia have been banned for production since 2020. This is due to the fact that in 2014 Russia signed the Minamata Convention on Mercury, which requires the production, export and import of goods containing mercury and mercury compounds to be stopped.

The advantages of mercury thermometers are their high accuracy (0.1°C error) and reliability. Mercury expands itself due to heat, does not require batteries and microcircuits. But these benefits are outweighed by the health risks posed by mercury vapor from a broken appliance.

Electronic thermometers are more “capricious”, although formally their accuracy is the same. They use a thermal sensor, so they need to be pressed closer to the body – and it is best to measure them orally or rectally. If you do not change the battery in time, the device will begin to “lie”.

But infrared thermometers have lower accuracy. This is due to the fact that the measuring beam passes through the air, which has its own temperature, and this distorts the result (up to 0.2°C). But it gives the result in a matter of seconds, and is convenient when you need to identify a febrile temperature.

A medical thermometer usually ends at 45°C. At 42°C, irreversible decomposition of proteins in the body begins, at 43°C, denaturation (thermal decay) of proteins in brain neurons, which leads to inhibition of brain functions, coma and death.

But even a temperature above 38°C (it is called febrile) is already quite difficult for the body. Blood pressure rises, heart rate rises, the number of decay products of bacteria in the blood increases, which can cause symptoms of poisoning and disrupt brain function (hence hallucinations).

Consequences of prolonged fever may include fainting, heart and kidney failure, dehydration, digestive and nervous system disorders.

As we found out, the temperature helps to fight the disease. Therefore, doctors usually advise taking antipyretics only when the temperature exceeds 38-38.5 ° C. But it depends on the state of the person himself, on how he tolerates the fever. In this case, an overdose of the drug can cause serious damage to the liver, kidneys, gastrointestinal tract, heart and brain.

If the fever is due to hormonal causes, such as hot flashes during menopause or a thyroid disorder (hyperthyroidism), these medicines will not work. In such cases, cooling treatments such as rubbing with a damp towel or bathing in cool water help.

As far back as the 1574 dictionary of John Whizels, it was noted that “fasting is an excellent remedy for fever.” But if the recommendation to drink more fluids has an obvious explanation (replenish fluid balance and remove the breakdown products of pathogens from the body), then what about the advice to eat less?

On the one hand, to maintain a high temperature, the body needs additional energy, which it can get from food. Fasting also creates additional stress. On the other hand, overeating and eating too spicy, unusual, unfamiliar foods can be harmful. The body may misinterpret certain substances as allergens and provoke a reaction.

Such a method exists. For example, in the middle of the 20th century, the German physician von Ardenne began to use it on cancer patients as a means of “last hope”. The fact is that cancer cells die at temperatures close to 42°C. Von Ardenne was able to heat patients up to 41.8°C. True, no more than 17% of them survived, but they were cured.

The “water” method was used for heating. The patient was placed in a special bath and with the help of water-jet devices placed over the patient, and poured over with heated water. Body temperature should have risen to 42-43°C. This procedure lasted about 6 hours under general anesthesia. The head was cooled with a special helmet. Later in the USSR, the idea of ​​heating with microwaves was developed.

Hyperthermia can help treat cancers that are difficult to operate on (eg, brain, mouth, and neck tumors). Heated tissues are more sensitive to ionizing radiation, which increases the effectiveness of radiotherapy. The problem is that it is not yet possible to concentrate the source of thermal radiation exactly at the site of the tumor without affecting other tissues.

Nevertheless, in recent years, the interest in therapeutic hyperthermia among scientists has been growing due to the development of new technologies. For example, one of the recent ideas involves the use of magnetic nanoparticles that can be injected directly into tumor tissue and heated from the inside using an alternating magnetic field.

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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.