What’s considered a fever and when to see a doctor

Humans – like all mammals – are warm-blooded, meaning our bodies stay warm, or at a fairly consistent temperature, even when the temperature of our surroundings change.

For most of us, our bodies tend to hover between 97 and 99 degrees Fahrenheit. But in certain circumstances, our body temperate rises, resulting in a fever.

“Your body’s immune system creates a fever to fight off infection,” said Sarah Joseph, MD. As an internal medicine and pediatrics specialist, Dr. Joseph treats children and adults of all ages for a wide range of illnesses.

Low-grade fever

The medical community generally defines a fever as a body temperature above 100.4 degrees Fahrenheit. A body temp between 100.4 and 102.2 degree is usually considered a low-grade fever.

“If the temperature is not high, it doesn’t necessarily need to be treated with medication,” Dr. Joseph said.

A low-grade fever usually doesn’t require treatment, unless the fever is occurring in a very young infant, or if it’s accompanied by other worrisome symptoms, such as confusion or the inability to eat or drink without vomiting.

To bring down a fever without medication, Dr. Joseph suggests wearing minimal clothing or bathing in lukewarm or cool water. You should also be sure to drink plenty of fluids to keep your body hydrated.

And keep in mind that even a mild fever could be a sign of a contagious illness. Washing your hands and covering your cough are always good practices.

“In the age of COVID-19, one of the things people should keep in mind is that if they are having any kind of fever that is persisting, they should probably go get tested,” Dr. Joseph said.

Not sure whether you need a test or where to get tested? Use our digital assistant, Clare, located in the lower right corner of the OSF HealthCare website.

High fever

When body temperature rises above 102. 2 degrees, it can be a sign of a more serious infection.

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Most fevers will resolve in a few days, but Dr. Joseph says some circumstances could be reason to see a provider, either in a primary care office or urgent care clinic.

Consider seeing a doctor if:

• Fever lasts longer than three to five days
• Fever doesn’t respond to fever-reducing medications, such as acetaminophen or ibuprofen (Tylenol or Advil)
• Other symptoms include confusion, neck stiffness or sensitivity to light

“Another reason to seek medical attention is if you don’t feel right about how things are going,” Dr. Joseph said.

Rarely, a fever could be a sign of a medical emergency.

Call 911 or go directly to an emergency room if you have a fever and any of the following symptoms:

• Seizures
• Severe abdominal pain
• Pain or burning with urination

• Shortness of breath or chest pain
• Difficulty holding down fluids
• Severe headache

Last Updated: February 10, 2022

View all posts by Laura Nightengale

Tags: emergency, fever, headache, urgent care

Categories: General

Fever – Better Health Channel

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Summary

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
by:

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

This page has been produced in consultation with and approved
by:

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

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Reviewed on: 21-06-2022

what to do, what temperature is considered high and why it is dangerous, causes and symptoms

Fever, fever – this is what we call an increase in body temperature. This is the most important defense mechanism of the human body and one of the main symptoms of infection. Most often, we encounter a fever with colds and flu. High temperatures cause some discomfort, but it helps to cope with the disease faster. We will tell you why adults have a fever, when it is necessary to bring down the temperature, and in what cases it is not worth it.

Why the temperature rises

¹

Body temperature can rise for various reasons: due to overheating, inflammation, hormonal imbalance. The processes of heat transfer in the human body are regulated by a small part of the brain – the hypothalamus. The temperature rises with any physical or chemical impact on it.

An increase in body temperature associated mainly with infections is called a fever. It develops when biologically active substances, cytokines, act on the hypothalamus. The immune system releases them into the blood in response to the inflammatory process. The production of cytokines is also enhanced by the waste products of microbes.

Fever is one of the main symptoms of an acute respiratory viral infection (ARVI). But it is also a protective reaction of the body, aimed at fighting the virus. When the temperature rises, the immune system synthesizes more leukocytes, which destroy or inactivate pathogenic microbes, and interferons, natural antiviral substances.

What temperature is considered high

^2.3

A temperature above 37˚C measured in the armpit is considered elevated. When measuring temperature in the oral cavity, a temperature of more than 37.2˚C is considered elevated, and in the rectum – more than 37.8˚C.

Types of fever:

● Subfebrile – 37.5–38˚C. Accompanies a chronic or easily flowing acute infection.

● Febrile – 38-39˚C. A frequent companion of most acute inflammatory processes – infectious and non-infectious.

● Pyretic (high) – 39-41˚C. This is one of the signs of a moderate flu. High fever is accompanied by symptoms that worsen well-being.

● Hyperpyretic (critically high) – more than 41˚C. It occurs in a severe form of influenza, causes life-threatening disorders of body functions.

What symptoms accompany fever

^{4, 5}

Subfebrile temperature is accompanied by weakness, feeling of weakness, headache, drowsiness, chills. At a temperature of 38˚C, the skin becomes hot, the cheeks turn red, the patient feels intense heat, dry mouth. Lips dry out and crack. With pyretic fever, nausea and vomiting may join. Hyperpyretic temperature is often accompanied by a disorder of consciousness, delirium.

Fever increases blood pressure and heart rate. An increase in temperature by one degree increases the pulse by 10-15 beats per minute.

What diseases occur with fever

⁶

The most common cause of fever in adults is acute respiratory viral infections (ARVI):

● Coronavirus, rhinovirus infection. This is SARS, affecting mainly the mucous membranes of the nasal cavity and pharynx. Symptoms: runny nose, redness and sore throat, sneezing, coughing. The temperature is subfebrile (37–38˚С) or febrile (38–39C).

● Influenza. Influenza viruses can immediately affect the lower respiratory tract and cause a deep chest cough. Infection is most often accompanied by severe intoxication, which is manifested by headache, aching throughout the body, and severe weakness. The temperature can reach pyretic (39-41˚C) and hyperpyretic (over 41˚C).

● Respiratory syncytial virus infection. It often affects the trachea and bronchi, in a quarter of the patients it leads to pneumonia. Symptoms are similar to the flu, with the difference that intoxication is less pronounced, signs of inflammation of the lower respiratory tract come to the fore – a deep cough with pain behind the sternum.

● Parainfluenza. The virus infects the nasal cavity, pharynx, larynx. The infection is accompanied by a runny nose, bouts of painful coughing, hoarseness, and sometimes a short-term loss of voice.

● Adenovirus infection. Runs with severe runny nose, sneezing, conjunctivitis. The eyes turn red, watery, there is pain and burning in the area of ​​​​the eyeballs and eyelids. Unlike other acute respiratory viral infections, adenovirus infection is often infected in spring and summer.

Other causes of fever:

● any infectious disease of a viral, bacterial, parasitic nature;

● non-infectious inflammations: acute pancreatitis, aspiration pneumonitis;

● allergic and autoimmune diseases: reaction to vaccination, rheumatoid arthritis, systemic lupus erythematosus;

● diseases of the thyroid gland, adrenal glands;

● oncological diseases: malignant tumors of internal organs, leukemia, lymphogranulomatosis;

● neurological pathologies: traumatic brain injury, cerebral hemorrhage;

● thermal (solar) stroke;

● psychogenic: prolonged emotional stress, neuroses, hysteria.

When temperature rise is dangerous

Fever poses a threat to health with a strong rise in temperature, when the thermometer shows 40˚C or more. This condition leads to dehydration, disruption of vital organs, and significantly increases the risk of thrombosis.

For healthy adults, an increase in temperature during SARS by 3˚C from the norm (36.6˚C) is not dangerous. However, for some people, even a febrile temperature can be harmful. At risk:

● Elderly people. After 65 years, it is more difficult for the body to adapt to an increase in temperature due to the age-related decrease in the ability to thermoregulate, the acquisition of chronic diseases.

● People with chronic diseases of internal organs: kidneys, cardiovascular, nervous system. Fever increases the load on these organs and can lead to an exacerbation of the disease.

What to do when the temperature is high

⁷

Fever helps to defeat the infection faster. With ARVI without fever, the infection takes longer, is accompanied by a pronounced deterioration in well-being, and is more often complicated. Therefore, it is worth suffering malaise for 2-3 days and not bringing down the temperature, provided that the body temperature does not exceed 38.5˚C. To make it easier to transfer the condition, avoid any physical activity, drink plenty of fluids, do not wrap yourself in blankets and excessively warm clothes that impair heat transfer.

But there are times when it is better to bring down the temperature:

● The thermometer reads over 39˚C.

● The rise in temperature is accompanied by a strong deterioration in the condition: loss of strength, poor sleep, nausea, vomiting.

● The patient is at risk.

Fever above 40˚C in adults requires emergency medical attention.

Non-drug methods. Wiping with a damp cloth or a weak vinegar solution will help to reduce the temperature. It is recommended to drink more warm drinks, such as tea with raspberry jam. Raspberries contain natural salicylates – substances that reduce fever. Drink should be moderately warm. Excessively hot or cold drinks and foods should be avoided.

Antipyretics. If non-drug treatments do not help, take an antipyretic medication. The safest drugs are paracetamol-based, which can be taken even by small children and pregnant women. Paracetamol is included in most combined anti-cold complexes, which additionally relieve nasal congestion and symptoms of intoxication in acute respiratory viral infections.

Antivirals. Lowering the temperature is not an end in itself in the treatment of SARS. Antiviral therapy should fight the causative agent of the infection. To do this, develop specific antiviral drugs that prevent the reproduction of the virus and infection of healthy cells. In the treatment of colds and flu, enisamium iodide has proven itself well. Its use reduces the acute clinical manifestations of viral intoxication. ⁸

Enisamia iodide at a dosage of 500 mg is part of the drug Nobasit ^® Forte ⁸ . Nobasit ^® Forte begins to act within 2 hours after taking the tablet ^8. In addition to the direct antiviral effect, enisamia iodide has a pronounced anti-inflammatory activity ^{9, 10} . The combined action leads to a 3-fold decrease in the severity of fever and other symptoms of intoxication (headache and muscle pain), starting from the second day of treatment ¹¹ . Also Nobasit ^® Forte helps to reduce the duration of the disease. ⁸

Briefly about the main

● Elevated is defined as a temperature above 37˚C measured in the armpit. If it is caused by an infection, this temperature is called a fever.

● The most common cause of fever in adults is SARS. Other causes – infections, non-infectious inflammation, heat stroke, stress, malignant tumors – are much less common.

● Fever brings recovery closer, but often it greatly affects well-being: it is accompanied by weakness, headache, body aches. In the elderly and people with common chronic diseases, fever often causes dangerous complications.

● Cool down in healthy adults should be above 38.5˚C and in at-risk people above 38˚C. If the temperature rises above 40˚C, it is worth calling an ambulance.

● First, try to bring down the temperature with home remedies – cool body wraps, tea with raspberry jam. If that doesn’t help, take an antipyretic medicine.

● Antipyretics will ease the fever but will not speed up recovery. To defeat the infection as soon as possible, take antiviral drugs, for example, Nobasit ^®
Forte.

¹ Tatochenko V.K., Uchaikin V.F. Fever // Pediatric pharmacology – 2006 – https://cyberleninka.ru/article/n/lihoradka

² Fugol D.S. An increase in body temperature in children and approaches to its correction // BC – No. 24, 2013 – https://elibrary.ru/item.asp?id=20603056

³ Vasilenko V.V. Measurement of body temperature // RMJ. – No. 29, 2008, S. 1948. https://www.rmj.ru/articles/istoriya_meditsiny/Izmerenie_temperatury_tela/

⁴ Dvovetsky L.I. Fever: to treat or not to treat // BC – No. 14, 2003 – https://www.rmj.ru/articles/obshchie-stati/Lihoradka_lechity_ili_ne_lechity/

⁵ Cheshik S.G., Vartanyan R.V. Respiratory syncytial viral infection: clinic, diagnosis, treatment // Children’s infections – No. 1, 2004 – https://cyberleninka.ru/article/n/respiratorno-sintsitialnaya-virusnaya-infektsiya-klinika-diagnosti…

⁶ Kalyuzhnaya L.I., Zemlyanoy D.A. Heat transfer disorders and fever // Pediatrician – T.6, No. 1, 2015 – https://cyberleninka.ru/article/n/narusheniya-teploobmena-i-lihoradka

⁷ Didkovsky N.A., Tanasova A.N. Fever. breast cancer. 2003; 4:189.

⁸ Instructions for medical use of Nobasit® Forte LP-006416.

⁹ Zyryanov S.K., Butranova O.I., Gaidai D.S., Kryshen K.L., Pharmacotherapy of acute respiratory infections caused by influenza viruses // Therapeutic archive – 2021, (1): pp. 17-27.

¹⁰ Kareva E.N., Fedotcheva T.A., Semeikin A.V., Kochina N.A., Krasnoshchok E.V., Shimanovsky N.L. Enisamia iodide – influence on the key components of the inflammatory process in acute respiratory viral infections // Therapeutic archive – 2022; 94 (11): pp. 1233 – 1238

¹¹ Lioznov D.A., Karnaukhova E.Yu., Zubkova T.G., Shakhlanskaya E.V., Evaluation of the effectiveness of the ARVI treatment regimen, including etiotropic (enisamia iodide) and symptomatic therapy // Therapeutic archive No. 3 – 2020.

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What to do at 40°C

Fever is one way the immune system fights infection ^1.2 . An increase in temperature begins with the entry of viruses, bacteria and other pathogens into the body. Next, a chain of reactions starts ^3.5 :

• Under the influence of pathogens, the body produces special substances – pyrogens ³ .
• Pyrogens enhance the production of mediators (mediators) of inflammation – prostaglandins ³ .
• Prostaglandins act on the hypothalamus – the part of the brain that controls the body’s thermoregulation ^3.5 .
• As pyrogens make the hypothalamus seem to have a low temperature, it begins to rearrange itself ⁵ . The thermoregulation center changes its “settings” so that the set point is above the norm ⁵ .
• After the restructuring of the hypothalamus, the muscles and skin vessels receive new “commands” ³ . To warm the body, the brain triggers small muscle contractions (shivering) to generate heat and constricts the blood vessels of the skin to save it. At this stage, a person feels cold – a feeling of chill familiar to almost everyone ^{3. 5} . In addition, muscle and joint pain, known as body aches, may also result from the action of prostaglandins ⁴ .

What causes a temperature of 40 °C?

Temperatures below 40°C are most commonly associated with infection ^1.14 , and not necessarily severe. Such high values ​​​​on the thermometer can also be observed with a cold, or, scientifically, with an acute respiratory viral infection (ARVI) ^14.15 . In the ARVI group, high fever is usually caused by adenoviruses and influenza viruses ^7.14 .

The flu starts abruptly, the state of health worsens suddenly. The first symptoms may be a temperature of 38-40 ° C, chills, weakness, eye pain and cough. Runny nose with influenza is less common and not at the onset of the disease, but at the end of the first day ¹⁴ . Flu fever lasts an average of 4 days ¹⁴ .

When infected with adenoviruses:

• the nasal cavity, mucous membrane of the eye, tonsils, pharynx are affected ⁶ ;
• symptoms appear slowly ⁶ ;
• The most disturbing thing is a severe runny nose and nasal discharge ¹⁵ ;
• lymph nodes may be enlarged ⁶ ;
• cold lasts up to 2 weeks ⁶ .

In a child, a temperature of 40 °C can also be a manifestation of herpangina. It is caused by enteroviruses, not herpes viruses, as many people mistakenly believe. With herpangina, bubbles form in the pharynx, which then burst, and in their place small ulcers appear that provoke a sore throat. Because of them, the child usually refuses to eat ⁸ .

As for bacteria, in case of a cold, they usually do not act independently, but join the viral disease ² . A bacterial infection may be suspected if a high temperature persists for more than 7 days ⁹ .

Temperature 40 °C without cold symptoms

It also happens that a high fever is not accompanied by cold symptoms. A possible cause of this condition is overheating (hyperthermia). In contrast to fever, when overheated, an increase in temperature up to 40 °C is associated with environmental conditions, and not with the effect of pyrogens on the hypothalamus ^3.