Fever in adults – Harvard Health

Fever is one of the body’s most effective ways of fighting infection. It is part of your body’s defense against infection-causing germs.

You get a fever most often when your body is trying to kill infectious invaders such as viruses or bacteria. A higher body temperature helps the immune system respond more vigorously to the attack, and makes it harder for these microbes to survive.

What is considered a fever in adults?

The average body temperature is 98.6° F (37°C). But “normal” body temperature varies from person to person. It also changes during the day, rising a bit after you eat or exercise. Body temperature is often higher in the afternoon than it is when you wake up in the morning.

Fever means a body temperature of 100.4° F (38°C) or higher.

High fever in adults

While any temperature above your normal temperature range is considered a fever, there are different levels of fever severity:

• Low-grade: 99. 1 to 100.4 F (37.3 to 38.0 C)
• Moderate-grade: 100.6 to 102.2 F (38.1 to 39.0 C)
• High-grade: 102.4 to 105.8 F (39.1 to 41 C)

When to worry about fever

If you have a fever over 104°F (40°C), you should call your doctor.

Seek medical help right away if you have a fever along with any of these symptoms:

• seizure
• loss of consciousness
• confusion
• stiff neck
• trouble breathing
• severe pain anywhere in the body
• swelling or inflammation of any part of the body
• vaginal discharge that is discolored or smells bad
• pain when urinating or urine that smells bad.

Causes of fever

An infection, such as the flu, is the most common cause of fever.

Other conditions can also cause a fever. These include diseases that produce inflammation, such as rheumatoid arthritis; reactions to drugs or vaccines; and even certain types of cancers.

Accompanying symptoms

The following symptoms may also accompany fever:

• sweats
• chills
• headache
• achy muscles
• lack of desire to eat
• rash
• restlessness
• weakness.

A very high fever can cause confusion, extreme sleepiness, irritability, and seizures.

Diagnosing the cause of a fever

To help determine why you have a fever, your doctor will ask you about:

• other symptoms such as coughing, abdominal pain, vomiting, diarrhea, or pain when urinating
• recent surgeries or injuries
• recent vaccinations
• new drugs you may be taking
• recent travel, particularly travel abroad.

How to treat a fever at home

By itself, fever is usually harmless, though a high fever can be miserable. These steps may help you feel better:

• Drink plenty of fluids to help cool your body and prevent dehydration.
• Eat light foods that are easy to digest.
• Get plenty of rest.
• Take ibuprofen (Advil, Motrin, or others), naproxen (Aleve, Naprosyn, or others), or acetaminophen (Tylenol, others) to help relieve head and body aches and lower your temperature.
• Take a slightly warm (not cool) bath, or apply damp washcloths to the forehead and wrists.

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How High of a Fever Is Dangerous for Adults?

5% to 20% of the US population gets the flu every year, resulting in 31.4 million outpatient visits annually. Whether you have the flu, the coronavirus, or another illness, one of the early symptoms is often a high-grade fever.

How high of a fever is dangerous for adults? Keep reading to find out.

By knowing how to recognize the symptoms, you can visit a doctor for treatment as soon as possible. Otherwise, the cause of your fever might lead to bigger complications in the future.

Don’t wait to get the help you need. Instead, learn how to recognize dangerous fever levels with this guide. 

A Little About Fevers

A fever is an elevation in body temperature. Usually, a body temperature above 98.6 F is considered elevated. However, a fever isn’t considered significant until it reaches about 100.4 F.

How high of a fever is dangerous for adults? Another below 100.4 F is considered a low-grade fever. If you have a fever above 100.4 F, you need to see a doctor.

Otherwise, your fever could result in delirium or convulsions. 

Possible Causes

Dangerous fever levels occur when your immune system is attacking a foreign invader, including a:

• Virus
• Bacteria
• Fungi
• Drug
• Toxin

These invaders are fever-producing substances called pyrogens that trigger your body’s immune response. Pyrogens tell your brain to increase your body temperature to fight off the infections. Common medical conditions associated with high-grade fevers include:

• Intracranial hemorrhage
• Thyroid storm
• Serotonin syndrome
• Sepsis
• Kawasaki syndrome
• Drug overdose

A fever is also a natural response to colds, flu, infections, and autoimmune disorders. 

Symptoms

You’ll likely notice different symptoms between a low-grade and high-grade fever.

For example, low-grade (pyrexia) fever symptoms include:

• Chills
• Sweats
• Headaches
• Thirst
• Low appetite
• Feeling hot
• Achy or tired eyes

An early high-grade (hyperpyrexia) fever can cause:

• Extreme sweating
• Dizziness
• Muscle cramps
• Fatigue
• Weakness
• Nausea

As the fever progresses, you might experience:

• Cool, moist, pale skin
• Mold confusion
• Vomiting
• Decreased urine
• Contracted pupils

When your fever hits above 106. 1 F, it can lead to:

• Extreme confusion
• Weak, fast heartbeat
• Dilated pupils
• Seizures
• Shallow, rapid breathing
• Loss of consciousness
• Hallucinations

If you’re wondering how high of a fever is dangerous for adults, a fever about 106.1 F is extremely dangerous. Seek medical attention immediately to prevent long-term consequences.

Treatment

You don’t always need to treat a low-grade fever. Remember, fevers indicate your body is fighting off an infection.

If you start to develop fever-related symptoms, however, you might want to use over-the-counter medications. These can include acetaminophen or ibuprofen. Make sure to rest and drink plenty of water.

If you develop a high-grade fever, however, the fever won’t go away until the infection is gone. Depending on the specific pathogen, you’ll likely need medical treatment.

Visit your local urgent care center right away if you develop a high-grade fever.

How High of a Fever Is Dangerous for Adults?: Know When It’s Time to See a Medical Professional

To recap, how high of a fever is dangerous for adults? If it’s above 106.1 F, it’s time to visit a medical professional.

Don’t wait to receive treatment. Contact us or just walk in to discuss your options.

Fever | Didkovsky N.A., Tanasova A.N.

L fever – an increase in body temperature as a result of a non-specific protective and adaptive reaction of the body, characterized by a restructuring of thermoregulation processes and occurring in response to exposure to pathogenic stimuli. There are fever infectious and inflammatory nature (viruses, bacteria, intracellular parasites) and non-infectious genesis (autoimmune processes, allergic diseases, tumors, metabolic disorders, the use of certain drugs, etc.) [2]. The regulation of body temperature is carried out with a complex interaction of the nervous, endocrine and immune systems. The most common trigger in the development of hyperthermia are exogenous pyrogens (bacteria, viruses, toxins, etc.), which, when ingested, stimulate the production of endogenous pyrogens by blood cells [4].

Fig.1. The mechanism of development of fever under the influence of exogenous and endogenous pyrogens. ACTH – ACTH, CRF – corticotropin-releasing factor, PGE2 – prostaglandin E2 (CECIL Textbook of Medicine, 19 h edition).

Currently, 11 cytokines are known to have pyrogenic activity, the most important of which are interleukins – IL-1 and IL-6, as well as tumor necrosis factor – TNF-a [4]. Endogenous pyrogens are produced by stimulated monocytes and macrophages. The properties of pyrogens are also possessed by a-, b- and g-interferons. IL-1 and TNF-a are transported with the blood stream to target cells that carry specific receptors for these cytokines, and act on thermosensitive neurons in the preoptic region of the hypothalamus through increased prostaglandin (PG) synthesis E ₂ and PGF _2a from arachidonic acid.

Fig. 2. Metabolism of arachidonic acid (according to A.A. Yarilin) ​​[3]. International abbreviations for prostaglandins (PG), leukotrienes (LT) and thromboxanes (Tx) are used.

The exact mechanism of “switching” of the thermoregulation center under the action of PG has not yet been established. The direct effect of cytokines on the nervous tissue is not excluded. An increase in body temperature activates metabolic processes, the functions of the nervous, endocrine, and immune systems (an increase in the production of antibodies, interferon, an increase in chemotaxis, phagocytic and bactericidal activity of neutrophils), an increase in the antitoxic function of the liver, and an increase in renal blood flow. IL-1 and TNF-a are able to enhance the immune response by activating T-cells and stimulating the production of IL-2. Under the action of IL-1, B-cell proliferation is enhanced, which is accompanied by an increase in antibody formation. It is important to note that these processes proceed most intensively at a temperature of 39°C. Under the action of endogenous pyrogens, the synthesis of “acute phase” proteins (fibrinogen, C-reactive protein, complement fractions B, C 3-4, alpha-glycoprotein, serum amyloid A, proteinase inhibitors) is stimulated by the liver, which play an important role in specific and non-specific protection. Hyperthermia is accompanied by a decrease in serum levels of iron, zinc and copper, which inhibits the growth and reproduction of microorganisms.

In a typical course, fever goes through the following phases or periods – a prodromal period, a period of temperature rise, a period of relative stability, a period of decrease in body temperature, each of which is accompanied by certain vegetative reactions. What changes accompany the development of fever?

1) Tachycardia. With an increase in body temperature by 1 ° C, an increase in heart rate by 10–15 beats per minute occurs.

2) It is possible to develop extrasystole, which is due to both the direct toxic effect of bacteria and viruses, and the activation of the sympathetic-adrenal system under the influence of cytokines.

3) In the phase of temperature rise, an increase in blood pressure is possible, and in the phase of temperature decrease, blood pressure drops to a collaptoid state against the background of a decrease in TPS.

4) Upon reaching the maximum body temperature, the process of sweating increases significantly (up to 1 liter of sweat per day is possible), which can contribute to a decrease in BCC and lead to a deterioration in the condition of patients with pathologies of the cardiovascular system. Fluid losses are also aggravated by a compensatory increase in respiratory rate at the height of fever.

5) At the height of fever and even after normalization of temperature, transient appearance in the urine of protein, casts and an increase in creatinine levels is possible. These changes are associated with the direct damaging effect of fever.

6) Fever affects the activity of various parts of the gastrointestinal tract, which is manifested by impaired secretion of digestive juices, impaired motility and absorption processes. As a result, there may be a decrease in appetite, the development of a syndrome of impaired absorption and constipation (the latter has a particularly adverse effect on elderly patients). Loss of appetite during fever is associated both with functional disorders of the gastrointestinal tract and with the direct influence of cytokines. So, with prolonged exposure to high concentrations of TNF-a (which has a second name in Western literature – “cachectin”) and partially IL-1, depletion may develop due to the suppression of hunger / appetite (which is most typical for chronic infections and oncological processes).

7) Against the background of fever, metabolic processes in cells increase sharply (with an increase in body temperature by 0. 6 ° C, the level of basal metabolism increases by approximately 10%), redox processes accelerate, and oxygen consumption increases. Hyperthermia can increase blood glucose levels, increasing protein catabolism (negative nitrogen balance). Loss of protein up to 300-400 grams per day is possible. A decrease in diuresis against the background of a reduced BCC can lead to the development of metabolic acidosis.

8) Changes in consciousness (from minor to the development of a delirious state) are associated with the release of b-endorphins under the influence of TNF-a and IL-1. The risk group includes young children, the elderly, patients with pathology of the cardiovascular system, as well as people who abuse alcohol.

9) Due to the immaturity of the central nervous system and the imperfection of the thermoregulation system in children under the age of 5 years, the development of febrile convulsions is possible.

10) An increase in body temperature can lead to the activation of latent herpesvirus infection (HSV-1). For reasons that are not completely clear, most often herpetic eruptions accompany diseases caused by a pyogenic bacterial infection (pneumococci, streptococci, meningococci), malaria, and rickettsiosis. Nasolabial herpes is a marker of reduced cellular immunity. It is important to note that subjective sensations during fever are of a different nature. Some patients are sensitive to even small fluctuations in body temperature, while others do not experience discomfort with a significant increase in temperature (for example, with pulmonary tuberculosis). However, in most cases, patients complain of weakness and malaise, headache, pain in the muscles and joints, chilling or excessive sweating, which “pushes” the doctor to prescribe antipyretics. When deciding on the need to prescribe non-steroidal anti-inflammatory drugs (NSAIDs), it is necessary to take into account both positive and potentially dangerous manifestations of fever. It must be remembered that fever, like any protective-adaptive reaction, with the depletion of compensatory mechanisms or with a hyperergic variant, can cause the development of pathological conditions. So, an excessive increase in temperature leads to inhibition of immune responses, dysfunction of parenchymal organs, the development of febrile convulsions, functional and degenerative disorders in the cardiovascular and central nervous system. A critical decrease in body temperature can contribute to the development of collapse due to a sharp drop in total peripheral resistance and aggravate the condition of patients with pathology of the cardiovascular system.

So in what case is it necessary to use antipyretics?

An increase in body temperature within 3°C does not have a damaging effect on the human body, however, its increase by more than 6°C (i.e. more than 42.2°C) leads to irreversible changes in the structures of the brain, which is a state incompatible with life. When deciding on the need to prescribe NSAIDs, it is necessary to take into account the age of the patient, the severity of the underlying and concomitant diseases, as well as the subjective tolerance of fever.

Currently NSAIDs are widely used in the symptomatic treatment of fever in ARVI. However, little attention is paid to non-drug (physical) methods of lowering body temperature, which is especially important in pediatric practice. I would like to remind you that physical methods to lower the temperature (such as wiping the body with a weak solution of vinegar, applying cold to the area of ​​​​large arteries, wet wrapping, a warm (not cold!) bath, an enema with water at room temperature) are recommended not only in the domestic , but also in modern foreign literature, can be quite effective and have no side effects. It is necessary to remember such rules for caring for patients with fever, such as an adequate drinking regimen, a sparing diet, mandatory ventilation of the room, and the prohibition to “wrap up” the patient, since the latter prevents heat transfer.

In febrile conditions on the background of infectious and inflammatory diseases, rectal suppositories Cefecon N are used as an antipyretic, anti-inflammatory and analgesic. Cefecon N suppositories are a unique combination of naproxen, caffeine and salicylamide, which ensures high antipyretic, analgesic activity. Cefecon H has a number of advantages over oral NSAIDs.

Before entering the systemic circulation, medicinal substances must pass through the stomach, small intestine, liver, where they are destroyed and adsorbed to a certain (sometimes significant) degree, which can lead to damage to this organ. Even if taken on an empty stomach, drugs enter the systemic circulation on average no earlier than 30 minutes later. When taking drugs orally in the form of powders and especially tablets, there is the greatest likelihood of their local irritating effect on the gastric mucosa.

With the rectal route of administration, the intake of substances adsorbed in the rectum is carried out simultaneously through the circulatory and lymphatic systems, which are especially developed in this area. In this case, an insignificant part of the adsorbed drugs enters the portal vein, which carries blood from the internal organs to the liver. Moreover, bioavailability from the rectal mucosa for a number of drugs is equivalent to that after intravenous administration. Thus, the introduction of NSAIDs in suppositories can reduce the risk of side effects from the gastrointestinal tract and ensure that the full dose of the drug is delivered, regardless of food intake and concomitant therapy (for example, antacids). In this regard, the use of NSAIDs in the form of rectal suppositories (Cefecon N) seems to be a very promising direction.

Despite the fact that, in the understanding of the patient, fever is often an undesirable manifestation of the disease, the doctor, when determining the strategy for treating the patient, must take into account the positive factors of the hyperthermic reaction. Moreover, the elimination of fever should not be the main goal of the therapy (which often occurs in the presence of SARS). It is well known that the course of an infectious disease without a temperature reaction may indicate that the patient has an immunodeficiency state and is an unfavorable prognostic factor.

1. Luchsheva Yu., Cold. How to deal with it. The effectiveness of symptomatic therapy for acute respiratory viral infections // Pharmaceutical Bulletin No. 37 (236), 2001.

2. NSAIDs: the role of rectal suppositories.//Russian Medical Journal, Vol. 10, No. 21(165), 2002, pp. 982–986.

3. Yarilin A.A., Fundamentals of immunology, M. “Medicine”, 1999, pp. 163–168.

4. Bruce Beutler, Steven M. Beutler, The Pathogenesis of Fever// CECIL Textbook of Medicine,19th edition, 1994, p.1568–1571.

5. Cranswick N, Coghlan D., Paracetamol efficacy and safety in children : the first 40 years// Am J Ther, 2000, 7(2): 135–41.

6. Glasow.J.F.T., Middleton B., Reye syndrome – insights on causation and prognosis// Arch Dis Child, 2001, 85, 351–353.

Hemorrhagic fevers

Hemorrhagic fevers are a group of acute infectious diseases caused by representatives of four types of viruses: arenaviruses, bunyaviruses, flaviviruses and filoviruses. Common to these diseases is severe intoxication and a characteristic thrombohemorrhagic syndrome.

Viruses that cause hemorrhagic fevers are widespread in many parts of the world. Some are also found in developed countries, but Africa, Asia and South America are endemic for most types of pathogens.

The course of hemorrhagic fever, depending on the pathogen, can vary from moderate to extremely severe. Mortality from individual variants of infection ranges from 10 to 90%. Certain variants of hemorrhagic fever lead to severe damage to internal organs and often to death.

The prognosis of the disease depends on the type of virus, the age and general condition of the patient, in particular on the activity of his immune system.

Synonyms English

Viral hemorrhagic fevers, hemorrhagicfevers, VHF, VHFs.

Symptoms

Symptoms of hemorrhagic fevers vary depending on the type of virus that caused the disease. Common manifestations for all infections are severe fever itself and increased bleeding. Symptoms in the initial stage of the disease are most often nonspecific, however, in the process of further development of the pathological process, signs of damage to certain organs and body systems may appear.

Main symptoms of hemorrhagic fevers:

• fever;
• weakness, dizziness;
• muscle pain;
• skin hyperemia;
• petechial rash on skin and mucous membranes;
• disturbance of consciousness;
• redness of the eyes;
• blood in stool, bloody vomiting;
• drop in blood pressure.

General information about the disease

Hemorrhagic fevers can be caused by four families of RNA viruses: arenaviruses (Arenaviridae), bunyaviruses (Bunyaviridae), filoviruses (Filoviridae) and flaviviruses (Flaviviridae). Arenaviruses cause Lassa fever, Argentinean, Brazilian, Venezuelan and Bolivian fevers, bunyaviruses cause Crimean-Congo fever, Rift Valley fever, hemorrhagic fever with renal syndrome, filoviruses cause Ebola fever, flaviviruses cause yellow fever, Dengue fever, etc.

“Reservoirs” of viruses are some animals and insects, most often small rodents, bats, mosquitoes, ticks. As a rule, certain types of hemorrhagic fevers are found mainly in the habitat of those animals that are the source of a particular pathogen. For example, the source of the Rift Valley fever virus, which is common in Africa, is mosquitoes. Crimean-Congo hemorrhagic fever occurs in Europe, Asia, Africa, it is spread by ticks. The source of some diseases, such as Ebola, remains unknown, suggesting that it may be bats. Some types of viruses are transmitted through the blood or semen of an infected animal or person, through unsterile needles. Certain causative agents of hemorrhagic fevers can be infected by inhalation of microparticles of faeces and urine of animal carriers.

All representatives of the viruses that cause hemorrhagic fevers are united by a common pathogenesis. They tend to affect the vascular endothelium, which explains the development of the hemorrhagic syndrome in most hemorrhagic fevers. After the virus enters the bloodstream through insect bites, scratches, abrasions, injections, the respiratory mucosa, a local reaction to infection is first formed, followed by viremia and a generalized lesion of the microcirculation system (the virus also infects the cells of the vascular wall). When the pathogen enters the bloodstream, it adheres to the cell membrane, penetrates into it, actively multiplies and spreads to other tissues of the body. This is accompanied by the release of biologically active substances that violate the permeability of blood vessels, the rheological properties of blood. A manifestation of this process is a rash, hyperemia of the skin, redness of the vessels of the sclera, internal bleeding may occur, accompanied by a sharp drop in blood pressure, shock. A number of viruses cause damage to the bone marrow, in particular megakaryocytes. Weakening of the body’s immune system, a weak or delayed response of protective mechanisms can lead to the rapid development of the pathological process, accompanied by massive bleeding, multiple organ damage.

Who is at risk?

• Those who work with infected people or animals, such as medical workers, biologists, pest control workers, livestock farm workers.
• Living in endemic areas.
• Intravenous drug users.
• Those who neglect barrier methods of contraception.

Diagnosis

Diagnosis is based on anamnesis, physical examination, results of laboratory and instrumental studies. When questioning the patient, attention is drawn to possible contact with the pathogen – travel to regions endemic for the disease, contact with animal carriers or infected people. The incubation period of most hemorrhagic fevers is 10-21 days, so the disease can develop after returning from a trip to a dangerous area. If hemorrhagic fever is suspected, it is necessary to conduct a series of studies in the hospital as soon as possible to differentiate the disease from other diseases and establish the type of pathogen:

• Complete blood count (without leukocyte formula and ESR). In a general blood test for hemorrhagic fevers, leukopenia and thrombocytopenia can be detected. In some cases, such as Lassa fever, these changes are absent. Hemoglobin levels may drop.
• Erythrocyte sedimentation rate (ESR). May be upgraded.
• Prothrombin index (PI) , activated partial thromboplastin time (APTT) are increased.
• Fibrinogen. Fibrinogen and platelet monitoring is used to detect possible disseminated intravascular coagulation.
• The test is used when a urinary tract infection is suspected.
• Culture of biological fluids: blood, urine, throat and nose swabs. Used to identify possible infectious agents.
• Detection of the causative agent of infection in the blood by polymerase chain reaction (PCR).
• Detection of antibodies to the infectious agent in the blood.

All diagnostic manipulations should be performed with extreme caution due to the high pathogenicity of pathogens.