Temperature 37.3 ° С Reasons for an increase, without symptoms, does not go away for a long time and what to do about it

February 17, 2021


9 minutes


Reasons for the temperature rise to 37.3 ° С Is the temperature of 37.3 ° C dangerous? Is it possible to bring down the temperature of 37.3 ° C and how to do it? Temperature 37.3 ° C in a child Why can there be a temperature of 37.3 ° C without symptoms? What if the temperature of 37.3 ° C does not pass for a long time? RINZA® and RINZASIP® with vitamin C at 37.3 ° C

Body temperature of 37.3 ° C is considered subfebrile, that is, not reaching the level of fever 1... It can appear in various diseases in adults and children, being one of the signs of inflammation. 1,2 ... But often there are situations when a thermometer reading at 37.3 ° C is found in a completely healthy person. That is why a single detection of subfebrile temperature is not a cause for alarm. It is taken into account if repeated measurements after a few hours give the same result. In this case, not only a constant temperature is important, but also its repeated rises. They can be detected both within one day and over several days.

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Reasons for the temperature rise to 37.3 ° С

Infectious and inflammatory diseases ... Of course, the most common cause of a temperature of 37.3 ° C is an infectious process. 1,3,4 ... More than 80% of cases in everyday medical practice are caused by it. And the dominant place in the list of all possible infections is occupied by the group of acute respiratory infections (acute respiratory diseases, mainly of a viral nature) 3.4 ... They are seasonal and epidemic. ARI can be caused by influenza viruses, parainfluenza, rhinos, corona and adenoviruses and some other not so common pathogens 4... Symptoms that develop with this include signs of intoxication (headache, malaise, muscle and joint pain, heart palpitations, general weakness), fever, catarrhal phenomena (runny nose, discomfort and sore throat, cough due to irritation of the back of the throat) 4... The severity of each symptom depends on the type of pathogen and the individual characteristics of the sick person.

Other infectious and inflammatory diseases can also lead to an increase in temperature to 37.3 ° C. Most often, sinusitis and other sinusitis, pyelonephritis, cystitis, bronchopulmonary pathology are diagnosed. Purulent inflammation of the skin (or mucous membranes) is also possible.

Non-communicable diseases. Non-infectious causes of fever include systemic diseases (rheumatism, rheumatoid arthritis, and others). An increase in temperature to 37.3 ° C is possible with overheating and heatstroke, in the early recovery period after operations, head injuries. In women, a rise in temperature is often noted after ovulation and during pregnancy. 1,3 .

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Is the temperature of 37.3 ° C dangerous?

An increase in body temperature is a universal protective reaction of the body in response to infection and the development of inflammation of any origin and localization. 4... It creates unfavorable conditions for the development and life of some microorganisms harmful to humans.

Moreover, this condition is usually not dangerous for our body. A temperature of 37.3 ° C does not lead to deactivation of key enzymes, does not contribute to the deformation of protein molecules and does not cause cell death. And although it is often accompanied by a feeling of malaise, vital organs are not affected. Even the sensitive and delicate nerve cells of the brain are not damaged. Therefore, it is a mistake to believe that a temperature of 37.3 ° C always poses some kind of danger to a sick person, even if he is feeling unwell.

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Is it possible to bring down the temperature of 37.3 ° C and how to do it?

The thermometer readings of 37.3 ° C are not a reason for the active use of various drugs and non-drug measures to combat fever. Such "treatment" will not necessarily be beneficial, although it may temporarily improve your well-being. So taking antipyretic drugs is not worth it, it is better to give the body the opportunity to use natural defense mechanisms to the maximum.

It is possible to bring down the temperature of 37.3 ° C with severe intoxication, the risk of developing cardiac and neurological complications, a tendency to a rapid deterioration of the condition with the development of a subjectively poorly tolerated fever 4... All these conditions require an early visit to a doctor and receive complex treatment, one of the components of which will be the administration of drugs with antipyretic and anti-inflammatory effects. In consultation with the doctor, non-drug measures can be used.

Often it is required not only to lower the temperature, but also to reduce the severity of catarrhal symptoms and intoxication. In this situation, you can use complex action means, one of which is RINZA® 5.

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Temperature 37.3 ° C in a child

A child's temperature of 37.3 ° C does not always indicate the presence of a disease. 2... This condition requires analyzing the situation and determining its true cause. What to do at a child's temperature of 37.3 ° C? First of all, to give up the desire to immediately give him an antipyretic drug approved by age. Other symptoms present need to be assessed 2.

For example, a child's cough accompanying a temperature of 37.3 ° C may be a sign of inflammation of the posterior pharyngeal wall, damage to the larynx, and involvement of the lungs in the process. Depending on the level and nature of the respiratory tract damage, treatment may include the use of various means. These can be vasoconstrictor drops from the common cold, sprays with an antibacterial component, lozenges for sucking, gargling, expectorants and mucolytics, for example syrup Dr. IOM ®6... In this case, the therapeutic scheme is determined by the doctor. 4, he also decides on the need to use antipyretic drugs. If a child has a temperature of 37.3 ° C due to a urinary infection, uroseptics will be the main drug. Meningitis requires antibiotic and neurologic therapy. But it is quite likely that the cause of the fever is not a disease. The thermometer can show 37.3 ° C when the child overheats, after intense physical activity and sometimes even after eating 2... It often happens that the temperature rises against the background of neurotic reactions - during the period of adaptation to kindergarten or school, parting with the mother, being in another stressful situation 2... There is no need to treat such conditions.

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Why can there be a temperature of 37.3 ° C without symptoms?

A temperature of 37.3 ° C without symptoms is not uncommon. The reasons for this condition may be:

  • neurosis, disorder of adaptation against the background of a stressful situation;
  • the consequences of the transferred infection - the so-called temperature tail;
  • condition after a closed craniocerebral injury;
  • the second phase of the menstrual cycle (after ovulation) in young women or climacteric syndrome in patients older than middle age;
  • first trimester of pregnancy;
  • latent urinary tract and respiratory tract infections, tuberculosis;
  • systemic connective tissue diseases 1,3 .

Thoughtless use of antipyretic drugs in such conditions not only will not give the expected effect, but can also lead to the development of complications. Therefore, a temperature of 37.3 ° C without symptoms in an adult requires a visit to a doctor and a comprehensive examination. 1.

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What if the temperature of 37.3 ° C does not pass for a long time?

Regularly occurring in the evenings or a constant temperature of 37.3 ° C can be a sign of chronic inflammation of various localization, a complicated course of the disease, the presence of endocrine, systemic or psychogenic disorders 1,3 ... Therapeutic tactics are based on a thorough diagnosis and impact on the true cause. A temperature of 37.3 ° C, which lasts for 2 months or more, requires the use of drugs prescribed by a doctor.

If, against the background of acute respiratory infections, the temperature of 37.3 ° C does not subside for a week, it is necessary to inform the doctor about it. Probably, a bacterial infection joined with the development of complications: sinusitis, otitis media, bronchitis. This may require the use of antimicrobial agents.

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RINZA® and RINZASIP® with vitamin C at 37.3 ° C

Fever, weakness, cough, sore throat against the background of colds, acute respiratory infections and influenza are often the basis for the use of symptomatic remedies with a complex effect. RINZA® and RINZASIP® products help to reduce the severity of symptoms of colds, acute respiratory viral infections and influenza due to antipyretic and analgesic effects, as well as the elimination of a runny nose and nasal congestion 5.7 .

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The information in this article is for reference only and does not replace professional medical advice. Consult a qualified professional for diagnosis and treatment.


  1. Tsogoeva L.M. Fever of unknown origin (to help the practitioner). / Tsogoeva L.M., Snopkov Yu.P. // Medicine of emergency conditions №5 (60), 2014, p. 40-45.
  2. E.G. Khramtsov. Prolonged subfebrile condition in childhood: modern aspects of diagnostic search. / E.G. Khramtsova, N.N. Muravyov // Pediatrician, volume IV, No. 2, 2013, p. 97-105.
  3. A.N. Smirnov. Differential diagnosis of hyperthermia in non-infectious pathology. Part 2. / A.N. Smirnov, E.P. Pogorelskaya // Archives of Internal Medicine. No. 6 (14), 2013; from. 53-58.
  4. A.A. Zaitsev. Influenza and acute respiratory viral infections: rational symptomatic therapy. // General Medicine No. 3, 2016, p. 21-28.
  5. Instructions for the use of RINZA®. Registration number: P N015798 / 01.
  6. INSTRUCTIONS for the medical use of the medicinal product DOCTOR MOM ®, Registration number: P N015983 / 01
  7. Instructions for the use of RINZAcip® with VITAMIN C. Registration number: LS-002579.

You will also be interested

Coronavirus: symptoms by day, temperature

The disease COVID-19, which causes the SARS-CoV-2 coronavirus strain, led to a pandemic in 2020. It is characterized by a polymorphic clinical picture. This means that the symptoms and severity of the course of the disease depend on many factors: the age of the infected person, the presence of chronic diseases, etc. The disease in different categories of patients differs in signs, which complicates its diagnosis.


Light form

COVID-19 is mildly tolerated by up to 80 patients. As a rule, these are people at a young age without any concomitant diseases. The symptoms of the disease, in this case, are similar to the signs of SARS. At the same time, there are certain differences that make it possible to recognize infection with a coronavirus infection.

Full recovery occurs within 14 days without any negative consequences for the body:

  • 1 day. The body temperature rises slightly, the indicators rarely exceed 37.2 ° C. There is also a slight malaise, which may well be attributed to fatigue. Nasal congestion and a deteriorating sense of smell may occur.

  • 2-4 days. General weakness and increased fatigue persist, but a critical temperature is not noted. Additionally, there is a sore throat and a mild unproductive cough. Problems with the sense of smell intensify, their sick people characterize them as "lack of odors." Sometimes there is an additional disorder of the digestive system, and there is no appetite.

  • 5-6 day. All of these symptoms subside and the condition improves. The intensity of the cough decreases, but the sense of smell does not return.

  • 7-14 days. There is a full recovery, all symptoms of COVID-19 completely disappear.

In children, a mild form, in most cases, does not manifest itself with any symptoms. Sometimes there may be signs of a mild cold without fever. But at the same time, the infection persists in biological fluids and waste products for a long time. This means that after infection, the child becomes an active carrier of the virus.

Medium form

The moderate severity of COVID-19 is characterized by a significant deterioration in well-being. In this case, pneumonia always develops, therefore hospitalization is indicated. After the onset of the first symptoms associated with fever and severe weakness, shortness of breath develops and pains in the joints of the muscles appear.

On days after infection with coronavirus infection, the following manifestations are observed:

  • 1 day. The body temperature rises to 37.5 ° C. Headaches and discomfort in joints and muscles occur. Nasal congestion is observed.

  • 2-4 days. The general condition deteriorates significantly, dyspeptic disorders and dizziness occur. Body temperature can rise to 38.5 ° C, so you need to lower it with special drugs. There is a persistent sore throat and bouts of prolonged unproductive cough, which indicates the spread of the infection to the lungs. Almost always, a sick person stops smelling.

  • 5-6 day. There is a deterioration in the patient's condition. Additionally, there are compressive pains in the chest. The body temperature does not drop below 38 ° C and it must be constantly brought down with antipyretic drugs. These symptoms are evidence of the development of viral pneumonia, which requires a complete examination and the appointment of appropriate treatment.

  • 7-14 days. With the correct course of treatment, the patient's condition improves. Cough, nasal congestion disappears, body temperature is normalized.

After stabilization of the condition, testing is carried out. If the result is negative, the person is considered recovered. But it may take another couple of weeks for a full recovery.

Severe form

A severe course of COVID-19 is noted in 5% of people infected with coronavirus infection. As a rule, in this case, patients additionally have serious pathologies and chronic diseases. The risk group includes older people. A characteristic sign of a severe course of the disease is the development of acute distress syndrome.

The disease often turns into a severe form from a moderate one in the case when the patient was not provided with timely assistance. The course of the disease by day:

  • Day 3. Body temperature rises sharply above 38 ° C. At the same time, it cannot be brought down for a long time, even with potent antipyretic drugs.

  • 3-4 day. There is a fever, which is accompanied by a strong, dry and deep cough. There are chest pains. A general deterioration in the condition provokes confusion and dizziness. Severe diarrhea may occur, accompanied by abdominal pain. An upset digestive system can lead to intoxication of the body.

  • 4-5 day. Severe shortness of breath appears even at rest. This indicates the defeat of large areas of the lungs. Sometimes there are attacks of suffocation, pain in the heart, heart rate increases.

  • 5-6 days. There are malfunctions in the functioning of the respiratory system, which leads to a drop in the level of oxygen in the blood. Such manifestations can lead to a complete cessation of breathing, therefore, it is required to connect the patient to mechanical ventilation and conduct complex drug treatment.

In a severe form of COVID-19, recovery can occur no earlier than a month after infection. But at the same time, you will need to additionally undergo rehabilitation for at least one and a half months. The risk group includes older people with serious pathologies of the cardiovascular and endocrine systems, cancer and weak immunity. There is also a risk of developing severe COVID-19 in smokers.

Causes of fever without signs of a cold

An increase in temperature or fever is observed in almost all acute infectious diseases, as well as during an exacerbation of certain chronic diseases. And in the absence of catarrhal symptoms, doctors can establish the cause of the patient's high body temperature by isolating the pathogen either directly from the local focus of infection, or from the blood.

It is much more difficult to determine the cause of the temperature without signs of a cold, if the disease arose as a result of exposure to the body of opportunistic microbes (bacteria, fungi, mycoplasma) - against the background of a decrease in general or local immunity. Then it is necessary to conduct a detailed laboratory study not only of blood, but also of urine, bile, sputum and mucus.

In clinical practice, cases of persistent - for three or more weeks - an increase in temperature without signs of a cold or any other symptoms (with values ​​above + 38 ° C) is called a fever of unknown origin.

The "simplest" case of a temperature of + 39 ° C without signs of a cold (in the sense of diagnosis, of course) refers to its appearance after a person's trip to hot foreign lands (especially to Africa and Asia), where he was bitten by a mosquito infected with parasites of the Plasmodium species. That is, in addition to souvenirs from the trip, a person brings malaria. The first sign of this dangerous disease is fever, to which headache, chills and vomiting are added. According to the WHO, between 350 million and 500 million people worldwide are infected with malaria every year.

The causes of fever without signs of a cold can be associated with diseases such as:

  • inflammatory diseases of bacterial origin: endocarditis, pyelonephritis, osteomyelitis, pneumonia, tonsillitis, andexitis, sinusitis, meningitis, prostatitis, inflammation of the uterine appendages, sepsis;
  • infectious diseases: tuberculosis, typhus and relapsing fever, brucellosis, Lyme disease, HIV infection;
  • diseases of viral, parasitic or fungal etiology: malaria, infectious mononucleosis, candidiasis, toxoplasmosis, syphilis;
  • oncological diseases: leukemia, lymphoma, tumors of the lungs or bronchi, kidneys, liver, stomach (with and without metastases);
  • systemic inflammation, including those of an autoimmune nature: polyarthritis, rheumatoid arthritis, rheumatism, rheumatoid arthritis, polymyalgia rheumatica, allergic vasculitis, periarthritis nodosa, systemic lupus erythematosus, Crohn's disease;
  • endocrine diseases: thyrotoxicosis.

An increase in temperature indicators can be caused by changes in the hormonal sphere. For example, during a normal menstrual cycle, women often have a temperature of + 37-37.2 ° C without signs of a cold. In addition, women with early menopause complain of unexpected sharp increases in temperature.

Fever without signs of a cold, the so-called subfebrile fever, often accompanies anemia - a low level of hemoglobin in the blood. Emotional stress, that is, the release of an increased volume of adrenaline into the bloodstream, can also raise body temperature and cause adrenaline hyperthermia.

According to experts, a sudden spasmodic rise in temperature can be caused by taking medications, including antibiotics, sulfonamides, barbiturates, anesthetics, psychostimulants, antidepressants, salicylates, and also some diuretics.

In rare enough cases, the causes of temperature without signs of a cold lie in the diseases of the hypothalamus itself.

trusted-source[1], [2], [3], [4], [5]


Our expert: Sabina Gadzhievna Moiseeva, general practitioner, family doctor,

physiotherapist, work experience - 19 years.

Low-grade fever, that is, a temperature in the range between 37.4 and 38, which lasts for a long time, is a very unpleasant symptom. A person may not even be bothered by anything else, and, moreover, he may not feel a rise in temperature, but be, however, unhealthy. Let's try to understand what subfebrile fever is and what diseases can increase the temperature for a long time to “average” figures.

Features of human thermoregulation

So, first, let's figure out what subfebrile condition is. In the literature, this is the name for the temperature above 37.4, but below 38 degrees, although more often this term means fever, "hanging" at the numbers 37.3 - 37.7, and we are not talking about a one-time increase in temperature, but about regular violations in the temperature curve. Another feature of subfebrile condition is that most often a person does not feel his temperature, that is, he does not have symptoms that we often experience when the numbers increase: headache, chills or fever, bone aches, weakness, sweating. He may feel good, go to work, live a normal life, and experience only weakness and malaise. Often a person learns about his subfebrile status by chance when he decides to measure his temperature.

A normal temperature for a person is considered to be in the range from 35.5 to 37.4 degrees, inclusive, that is, 37 is not a fever yet, and 36 is not a breakdown. This is natural: during sleep, metabolic processes slow down and the body temperature decreases, and in the waking state, especially during physical and emotional stress, the body temperature rises. Therefore, morning temperatures are usually lower than daytime or evening temperatures. Also, the body temperature depends on the method and place of its measurement, the sex of the measuring person, his age and condition. And in women - from the phase of the cycle or pregnancy. The child's body temperature is more labile and depends to a greater extent on the ambient temperature and on the state of the body. In addition, each person has their own individual norms, such as, for example, there are adapted norms for pulse rate and blood pressure.

All these features should be taken into account when drawing up a temperature curve - a graph with which you can determine whether a person really has subfebrile condition. It should also be remembered that different parts of the human body have different temperatures. And if the temperature in the armpit is 36.6 ° C, then in the mouth it will be about 37 ° C, and in the rectum even higher - 37.5 ° C.

To draw up a schedule correctly, it is necessary to keep a diary for several days and measure the temperature at different points - under the arm, in the mouth, rectally, at the same time and under the same conditions (immediately after sleep, before meals, after eating , before and after bathing, etc.). Then, based on the diary, a graph is drawn up that clearly demonstrates at what time of the day the temperature rises. We can talk about true subfebrelit when the temperature rises at all points of measurement.

Diseases that can cause low-grade fever


Subfebrality differs from infectious fever in that it lasts for a long time and is most often asymptomatic. In acute infectious diseases, the temperature rises sharply, accompanied by symptoms of intoxication (bone aches, headache) and is accompanied by active complaints (catarrhal phenomena - runny nose, sore throat, cough, etc.) and decreases to normal after recovery. Low-grade fever is often impossible to bring down even with antipyretic drugs.

The so-called temperature center, located in the hypothalamus, a part of the brain, is responsible for thermoregulation in the body. It receives information from receptors, and, depending on it, either triggers cooling or warming mechanisms. Hormones are also involved in these processes, a malfunction of which can also be the cause of subfebrile condition. But it is important to understand that if the body temperature rises, it means:

- foreign proteins have appeared in the blood and the body reacts to their appearance (this is what happens with infections - bacterial and viral) and inflammation - this temperature is called fever;

- there was some other malfunction in the body that affected the work of the temperature center (for example, the hormonal background changed);

- there was some direct effect on the temperature center (traumatic brain injury, brain tumor).

Acute viral infections cannot cause prolonged subfebrile condition, and the persistence of an elevated body temperature signals the addition of a secondary infection, more often bacterial, i.e. about the complication. But sluggish inflammatory, bacterial or viral processes can just increase the body temperature to average values. Often this "chronic" temperature can be caused by diseases of the urinary system (chronic pyelonephritis, cystitis of a sluggish course), diseases of the gastrointestinal tract (pancreatitis, cholecystitis, colitis), inflammatory processes of the genitourinary system. Most likely, other unexpressed symptoms will also be observed, depending on where the inflammation is localized - pain, weakness, loss of appetite, stool disturbance, nausea, clouding of urine, changes in feces, etc. However, often due to the fact that the inflammation is sluggish, a person may not notice the deterioration of health for a long time or not pay attention to it, and the temperature in this case will be the only symptom.

In acute viral diseases (measles, rubella, chickenpox, flu), the exception is the so-called "temperature tails" - a condition when a low temperature continues to persist for a long time after recovery. This temperature returns to normal within a few weeks (sometimes it lasts up to six months), but other possible post-infectious complications must be excluded.

Separately, it must be said about viral diseases of herpetic origin, causing prolonged subfebrile condition. First of all, it is capable of causing "chronic fatigue syndrome" Epstein-Barr virus, cytomegalovirus, which causes infectious mononucleosis, herpes viruses type 1 and 2, and herpes virus type 6. All of them come to us "under the masks" of acute viral diseases, but they remain in the body for a long time, and it is not always easy to recognize them.


In addition, infectious diseases such as toxoplasmosis, tuberculosis, viral hepatitis, and HIV can cause prolonged low temperatures. At the same time, the clinical symptoms of these dangerous diseases can be erased, that is, in addition to temperature, weakness, loss of appetite, increased fatigue and sweating, the patient may no longer notice anything. Infection with helminthic invasions can also increase the temperature for a long time to subfebrile values. And although this is not the most common cause of fever, it cannot be ruled out, especially if the patient is experiencing discomfort in the intestines and is losing weight.

In case of oncological diseases, foreign proteins also appear in the human body, from which he is trying to get rid of. That is why prolonged low-grade fever can be a sign of cancer, sometimes the first and the only one for a long time.

Autoimmune disorders, as a result of which the body begins to perceive its own healthy cells as a foreign protein and destroy them, can also be accompanied by prolonged low-grade fever. The most common of them are rheumatoid arthritis, systemic lupus erythematosus, Crohn's disease. Symptoms of autoimmune diseases can vary depending on which tissue is being destroyed. With arthritis, the patient may experience pain in the joints, with Crohn's disease - abdominal pain, problems with stool up to the appearance of blood in the stool, with systemic lupus erythematosus - joint and muscle pain, in addition, this disease is characterized by the appearance of a specific rash.

Another group of pathologies that can cause temperature rises are associated with hormonal changes. Most often this occurs with diseases of the thyroid gland, especially hyperthyroidism, with excessive production of hormones by the gland. Metabolism in this case is accelerated, the temperature rises to low values ​​(most often - up to 37.5). The patient may also experience weight loss, shortness of breath, sweating, irritability, tremors, and tachycardia. In addition, hormonal changes can increase body temperature in adolescents, women in menopause, as well as in pregnant and breastfeeding women, especially at the very beginning of lactation (during lactation, the body temperature in the axillary region is higher than normal, therefore it is measured more often in the elbow bend) ... As for pregnancy, sometimes a rise in temperature is the first sign that a woman is expecting a baby. It can appear even before the delay in menstruation and earlier than other symptoms - nausea, dizziness, swelling of the mammary glands. This is a variant of the norm that does not require medical treatment.

Tumors of the brain, including benign ones, as well as traumatic brain injuries, affect the work of the temperature center located in the brain, therefore, in these conditions, a person can also experience prolonged subfebrality. However, temperature rises can often be caused by psychogenic reasons - stress, neuroses, depression. In medicine, there are also concepts such as "thermoneurosis" and "subfebrality of unclear etiology." These diagnoses are often caused by disturbances in the patient's emotional state, but more often this is a diagnosis of exclusion and can only be talked about after a complete examination and exclusion of other pathologies.

Everyone should monitor their temperature and measure it regularly, even when they are well. In case of unexplained rises, you should immediately contact a therapist or pediatrician. The examination plan will depend on the examination, collection of complaints and medical history.

It often happens that while the patient is undergoing examination, the temperature normalizes on its own, however, in no case should this symptom be left unattended.

Author: Julia GVOZDEVA

36.6 is not a constant body temperature of a healthy person, if you monitor it during the day, then this value will fluctuate slightly. The lowest result, about 36 degrees, will be at the time of morning sleep. If a person is hot after physical activity, then the temperature may rise slightly

Body temperature is affected by heat, humidity, clothes that are too warm. Women experience a slight jump in temperature (by half a degree) on certain days of the menstrual cycle. But this will be a one-time promotion. An increase in temperature from 37.2 to 37.9 in a period of more than a month may become a cause for concern - this is a subfebrile temperature.

If the subfebrile temperature lasts more than two weeks, and it is accompanied by symptoms such as fatigue, poor sleep, shortness of breath, then you should not postpone the appointment of a therapist. Often, subfebrile signals a malfunction in the body, when other symptoms have not yet appeared.

Causes of low-grade fever

There are diseases that provoke a slight increase in temperature over a long period.

  • Chronic infectious process (tuberculosis, chronic diseases of the nasopharynx, pancreatitis, cholecystitis, prostatitis, adnexitis, bacterial endocarditis, chlamydia, syphilis, HIV infection).
  • Inflammatory process
  • Oncology
  • Autoimmune diseases (rheumatism, ulcerative colitis, drug allergies, arthritis, postinfarction syndrome)
  • Parasites
  • Endocrine system pathologies (thyrotoxicosis, severe menopause)
  • Thermoneurosis (autonomic dysfunction affecting heat transfer)

If the cause of the fever is an infection, then it is characterized by:

  • decrease after taking antipyretic;
  • poor tolerance;
  • fluctuations are noted throughout the day.

But there are reasons when a healthy person has a subfebrile temperature:

  • overheating
  • under stress
  • when taking certain medications
  • hereditary factor when a child is born and lives with a fever
  • when the hypothalamus is activated
  • during pregnancy
  • before menstruation.

This temperature does not lend itself to the action of antipyretic drugs, is easily tolerated and does not have pronounced daily fluctuations.

An examination will help to find out the reason.

Analyzes and studies at subfebrile temperature.

You should always start with a general practitioner. It is the therapist who will direct you for primary tests, and then, after the results obtained, will recommend the appointment of a narrow specialist: endocrinologist, cardiologist, gynecologist, otolaryngologist, infectious disease specialist.

Fever for more than two weeks?

You need to pass:

  • General analysis of blood and urine (increased leukocytosis, protein in the urine)
  • Blood for hepatitis B and C, HIV and syphilis
  • Sputum culture for Mycobacterium tuberculosis
  • Urine culture (genital infections) and blood culture (sepsis).

To do:

  • Chest x-ray (tuberculosis, lung abscess)
  • Electrocardiogram (bacterial endocarditis)
  • Ultrasound of the small pelvis (inflammatory diseases)
  • Abdominal ultrasound

If, after the results obtained, the cause is not established, then the patient is sent to take a blood test:

  • for hormones
  • for rheumatoid factor
  • for tumor markers.

Menzhevitskaya Tatiana Ivanovna

Body temperature is one of the most important physiological parameters that indicate the state of the body. We all know from childhood that normal body temperature is +36.6 ºC, and a temperature rise of more than +37 ºC indicates some kind of disease.

Subfebrile temperature: Why the temperature is 37

What is the reason for this condition? The rise in temperature is an immune response to infection and inflammation. The blood is saturated with temperature-raising (pyrogenic) substances produced by pathogenic microorganisms. This, in turn, stimulates the body to produce its own pyrogens. Metabolism is somewhat accelerated to make it easier for the immune system to fight the disease. Fever is usually not the only symptom of the disease. For example, with colds, we feel typical symptoms for them - fever, sore throat, cough, runny nose. With mild colds, the body temperature can be +37.8 ºC. And in case of severe infections, such as the flu, it can rise to + 39-40 ºC, and aches in the whole body and weakness can be added to the symptoms.

Danger of increased temperature

In such situations, we know perfectly well how to behave and how to treat the disease, because its diagnosis is not difficult. We gargle, take anti-inflammatory drugs and antipyretics, if necessary, take antibiotics, and the disease gradually goes away. And after a few days, the temperature returns to normal. Most of us have faced a similar situation more than once in our lives.

However, it happens that some people experience slightly different symptoms. They find that their temperature is higher than normal, but not by much. We are talking about subfebrile - about a temperature in the range of 37-38 ºC.

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Is this condition dangerous? If it does not last long - for several days, and you can associate it with some kind of infectious disease, then no. It is enough to cure it, and the temperature will drop. But what if there are no visible symptoms of a cold or flu?

Here it must be borne in mind that in some cases colds may have blurred symptoms. Infection in the form of bacteria and viruses is present in the body, and the immune forces react to their presence by raising the temperature. However, the concentration of pathogenic microorganisms is so low that they are unable to cause the typical symptoms of a cold - cough, runny nose, sneezing, sore throat. In this case, the fever can pass after these infectious agents die and the body recovers.

Especially often, a similar situation can be observed in the cold season, during epidemics of colds, when infectious agents can repeatedly attack the body, but stumble upon a barrier of embattled immunity and do not cause any visible symptoms, except for an increase in temperature from 37 to 37 ,five. So if you have 4 days 37.2 or 5 days 37.1, and you feel good at the same time, this is not a cause for concern.

However, as you know, colds rarely last more than one week. And, if the elevated temperature lasts longer than this period and does not subside, and no symptoms are observed, then this situation is a reason to think seriously. After all, a constant subfebrile condition without symptoms can be a harbinger or a sign of many serious diseases, much more serious than the common cold. These can be diseases of both infectious and non-infectious nature.

Subfebrile temperature: Why the temperature is 37

Measurement technique

However, before worrying in vain and running to doctors, you should exclude such a banal reason for subfebrile condition as measurement error ... After all, it may well happen that the cause of the phenomenon lies in a faulty thermometer. As a rule, this is the fault of electronic thermometers, especially cheap ones. They are more convenient than traditional mercury ones, however, they can often show incorrect data. However, mercury thermometers are not immune to errors. Therefore, it is better to check the temperature on another thermometer.

Body temperature is usually measured in the armpit ... Rectal measurement is also possible and oral measurement ... In the last two cases, the temperature may be slightly higher.

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Measurement should be taken while sitting, calm, in a room with normal temperature. If the measurement is taken immediately after intense physical activity or in an overheated room, then the body temperature in this case may be higher than usual. This circumstance should also be taken into account.

One should also take into account such a circumstance as temperature changes during the day ... If in the morning the temperature is below 37, and in the evening - the temperature is 37 or slightly higher, then this phenomenon may be a variant of the norm. For many people, the temperature can change slightly during the day, rising in the evening hours and reaching values ​​of 37, 37.1. However, as a rule, the evening temperature should not be subfebrile. In a number of diseases, a similar syndrome, when every evening the temperature is above normal, is also observed, therefore, in this case, it is recommended to undergo an examination.

Possible causes of prolonged subfebrile condition

If you have an elevated body temperature without symptoms for a long time, and you do not understand what this means, then you should consult a doctor. Only a specialist after a thorough examination can say that this is normal or not, and if it is not normal, then what is the cause. But, of course, it is not bad to know for yourself what can cause such a symptom.

What conditions of the body can cause prolonged subfebrile condition without symptoms:

  • variant of the norm
  • changes in hormonal levels during pregnancy
  • thermoneurosis
  • temperature tail of infectious diseases
  • oncological diseases
  • autoimmune diseases - lupus erythematosus, rheumatoid arthritis, Crohn's disease
  • toxoplasmosis
  • brucellosis
  • tuberculosis
  • helminthic invasions
  • latent sepsis and inflammation
  • foci of infection
  • thyroid disease
  • anemia
  • drug therapy
  • AIDS
  • intestinal diseases
  • viral hepatitis
  • Addison's disease

Variant of the norm

Statistics say that 2% of the world's population has a normal temperature slightly above 37. But if you do not have a similar temperature since childhood, and subfebrile condition has appeared only recently, then this is a completely different case, and you do not belong to this category of people.

Pregnancy and lactation

Body temperature is regulated by hormones produced in the body. At the beginning of such a period of a woman's life as pregnancy, a restructuring of the body occurs, which, in particular, is expressed in an increase in the production of female hormones. This process can cause overheating of the body. Typically, a temperature around 37.3ºC for pregnancy should not be a major concern. In addition, the hormonal background is subsequently stabilized, and the subfebrile condition passes.

Usually, starting in the second trimester, the woman's body temperature stabilizes. Sometimes subfebrile condition can accompany the entire pregnancy. As a rule, if a fever is observed during pregnancy, then this situation does not require treatment. Sometimes a subfebrile condition with a temperature of about 37.4 can also be observed in women who are breastfeeding, especially in the first days after the appearance of milk. Here, the reason for the phenomenon is similar - fluctuations in the level of hormones.


Body temperature is regulated in the hypothalamus, one of the brain regions. However, the brain is an interconnected system and processes in one part of it can influence another. Therefore, such a phenomenon is very often observed when, during neurotic states - anxiety, hysteria - the body temperature rises above 37.

This is also facilitated by the production of increased amounts of hormones in neuroses. Prolonged subfebrile condition can accompany stress, neurasthenic states, many psychoses. With thermoneurosis, the temperature usually returns to normal during sleep.

To exclude such a reason, it is necessary to consult with a neurologist or psychotherapist. If you really have a neurosis or anxiety associated with stress, then you need to undergo a course of treatment, since loose nerves can cause much greater problems than subfebrile condition.

Temperature tails

You should not discount such a banal reason as a trace from a previously transferred infectious disease. It is no secret that many flu and acute respiratory infections, especially those with a severe course, lead the immune system to a state of increased mobilization. And in the event that infectious agents are not completely suppressed, then the body can maintain an elevated temperature for several weeks after the peak of the disease. This phenomenon is called a temperature tail. It can be observed in both an adult and a child.

Therefore, if the temperature + 37 ºС and above lasts a week, then the causes of the phenomenon may lie precisely in the previously transferred and cured (as it seemed) disease. Of course, if you were ill shortly before the discovery of a constant subfebrile temperature with some infectious disease, then there is nothing to worry about - subfebrile condition is precisely its echo. On the other hand, such a situation cannot be called normal, since it indicates a weakness of the immune system and the need to take measures to strengthen it.

Oncological diseases

This reason also cannot be discounted. Often, it is subfebrile condition that is the earliest sign of a tumor that has appeared. This is explained by the fact that the tumor throws pyrogens into the bloodstream - substances that cause an increase in temperature. Especially often subfebrile condition accompanies oncological diseases of the blood - leukemia. In this case, the effect is due to a change in the composition of the blood.

To exclude such diseases, it is necessary to undergo a thorough examination and take a blood test. The fact that a persistent rise in temperature can be caused by such a serious illness as cancer makes this syndrome serious.

Autoimmune diseases

Autoimmune diseases are caused by an abnormal response of a person's immune system. As a rule, immune cells - phagocytes and lymphocytes attack foreign bodies and microorganisms. However, in some cases, they begin to perceive the cells of their body as foreign, which leads to the appearance of the disease. In most cases, connective tissue is affected.

Almost all autoimmune diseases - rheumatoid arthritis, systemic lupus erythematosus, Crohn's disease, are accompanied by an increase in temperature to 37 and above without symptoms. Although these diseases usually have a number of manifestations, they may not be noticed at an early stage. To exclude such diseases, you must be examined by a doctor.


Toxoplasmosis is a very common infectious disease that often proceeds without noticeable symptoms, except for fever. Pet owners, especially cats that carry bacilli, are often sick with it. Therefore, if fluffy pets live in your house and the temperature is subfebrile, then this is a reason to suspect this disease.

You can also get the disease through poorly cooked meat. To diagnose toxoplasmosis, a blood test should be taken for infection. You should also pay attention to symptoms such as weakness, headaches, decreased appetite. The temperature with toxoplasmosis does not go astray with the help of antipyretics.


Brucellosis is another disease caused by an animal-borne infection. But this disease is most often affected by farmers who deal with livestock. The disease in the initial stage is expressed in a relatively low temperature. However, as the disease progresses, it can take on severe forms, affecting the nervous system. However, if you do not work on a farm, then brucellosis can be ruled out as a cause of hyperthermia.


Alas, consumption, notorious for the works of classical literature, has not yet become the property of history. Millions of people are currently suffering from tuberculosis. And this disease is now characteristic by no means only for places that are not so remote as many believe. Tuberculosis is a serious and stubborn infectious disease that is difficult to treat even by the methods of modern medicine.

However, the effectiveness of treatment largely depends on how quickly the first signs of the disease were detected. The earliest signs of the disease include subfebrile condition without other clearly expressed symptoms. Sometimes temperatures above 37 ºC may not be observed all day, but only in the evening.

Other symptoms of tuberculosis include sweating, fatigue, insomnia, and weight loss. To accurately determine whether you have tuberculosis, you need to perform an analysis for tuberculin (Mantoux test), as well as do a fluorography. It should be borne in mind that fluorography can reveal only the pulmonary form of tuberculosis, while tuberculosis can also affect the genitourinary system, bones, skin and eyes. Therefore, you should not rely only on this diagnostic method.


About 20 years ago, a diagnosis of AIDS meant a sentence. Now the situation is not so sad - modern drugs can support the life of a person infected with HIV for many years, or even decades. It is much easier to become infected with this disease than is commonly believed. This disease affects not only representatives of sexual minorities and drug addicts. You can pick up the immune deficiency virus, for example, in a hospital with a blood transfusion, with casual sexual contact.

Constant subfebrile condition is one of the first signs of the disease. Let's note. that in most cases, the weakening of immunity in AIDS is accompanied by other symptoms - an increased susceptibility to infectious diseases, skin rashes, and stool disorders. If you have reason to suspect AIDS, you should immediately consult a doctor.

Helminthic invasions

Worms or helminths are usually called parasitic worms living in the human body. It is not so difficult to become infected with parasites, because the eggs of many of them live in the body of animals, in the ground or in water bodies. Failure to comply with the rules of hygiene leads to the fact that they enter the human body.

Many parasitic diseases can cause persistent subfebrile condition. As a rule, it is accompanied by digestive upset, but in many cases, especially if the parasites have settled not in the intestines, but in other tissues, these symptoms may not be present. You should also pay attention to such a common symptom as weight loss. Intestinal parasites are identified by stool analysis. Also, many parasitic diseases are diagnosed with a blood test.

Latent sepsis, inflammatory processes

Often, an infection in the body can be latent in nature, and do not show any signs other than fever. The foci of a sluggish infectious process can be located in almost any organ in the cardiovascular system, the gastrointestinal tract, in the bone and muscular systems. The urinary organs are most often affected by inflammation (pyelonephritis, cystitis, urethritis).

Often, subfebrile condition can be associated with infective endocarditis, a chronic inflammatory disease that affects the tissues surrounding the heart. This disease can have a latent character for a long time and not manifest itself in any other way.

Also, special attention should be paid to the oral cavity. This area of ​​the body is especially vulnerable to pathogenic bacteria because they can enter it regularly. Even a simple, untreated tooth decay can become a hotbed of infection, which will enter the bloodstream and cause a constant protective response of the immune system in the form of a rise in temperature. The risk group also includes patients with diabetes mellitus, who may have non-healing ulcers that make themselves felt through fever.

Diseases of the thyroid gland

Thyroid hormones such as thyroid stimulating hormone play an important role in the regulation of metabolism. Certain diseases of the thyroid gland can increase the release of hormones. An increase in hormones can be accompanied by symptoms such as increased heart rate, weight loss, hypertension, inability to tolerate heat, deterioration of hair and fever. Nervous disorders are also observed - increased anxiety, anxiety, distraction, neurasthenia.

An increase in temperature can also be observed with a lack of thyroid hormones. To eliminate the imbalance of thyroid hormones, it is recommended to take a blood test for the level of thyroid hormones.

Addison's disease

This disease is quite rare and is expressed in a decrease in the production of hormones by the adrenal glands. It develops for a long time without any special symptoms and is also often accompanied by a moderate increase in temperature.


A slight increase in temperature can also cause a syndrome such as anemia. Anemia is a lack of hemoglobin or red blood cells in the body. This symptom can manifest itself in various diseases, it is especially characteristic of severe bleeding. Also, an increase in temperature can be observed with some vitamin deficiencies, a lack of iron and hemoglobin in the blood.

Drug treatment

At a subfebrile temperature, the causes of the phenomenon may consist in taking medications. Many medications can cause fever. These include antibiotics, especially penicillin drugs, some psychotropic substances, in particular, antipsychotics and antidepressants, antihistamines, atropine, muscle relaxants, narcotic analgesics.

Very often, an increase in temperature is a form of an allergic reaction to a drug. This version is perhaps the easiest to check - it is enough to stop taking the drug that arouses suspicion. Of course, this must be done with the permission of the attending physician, since the withdrawal of the drug can lead to much more serious consequences than subfebrile condition.

Age up to a year

In infants, the causes of low-grade fever may lie in the natural processes of the body's development. As a rule, a person's temperature in the first months of life is slightly higher than that of adults. In addition, in infants, thermoregulation disorders can be observed, which is expressed in a small subfebrile temperature. This phenomenon is not a symptom of pathology and should go away on its own. Although, if the temperature rises in infants, it is still best to show them to the doctor to rule out infections.

Intestinal diseases

Many infectious intestinal diseases can be asymptomatic, except for an increase in temperature above normal values. Also, a similar syndrome is characteristic of some inflammatory processes in diseases of the gastrointestinal tract, for example, in ulcerative colitis.


Hepatitis types B and C are severe viral diseases that affect the liver. As a rule, prolonged subfebrile condition accompanies sluggish forms of the disease. However, in most cases, it is not the only symptom. Usually, hepatitis is also accompanied by heaviness in the liver, especially after eating, yellowness of the skin, pain in the joints and muscles, and general weakness. If you suspect hepatitis, you should consult a doctor as soon as possible, since early treatment reduces the likelihood of severe, life-threatening complications.

Diagnostics of the causes of prolonged subfebrile condition

As you can see, there are a huge number of potential causes that can cause a violation of the body's thermoregulation. And finding out why it happens is not easy. This can be time consuming and demanding. Nevertheless, there is always something from which such a phenomenon is observed. And a high temperature always says something, usually that something is wrong with the body.

As a rule, at home it is impossible to establish the cause of subfebrile condition. However, some conclusions about its nature can be drawn. All the reasons that cause an elevated temperature can be divided into two groups - associated with some kind of inflammatory or infectious process and not associated with it.

  • In the first case, taking antipyretic and anti-inflammatory drugs such as aspirin, ibuprofen or paracetamol can restore normal temperature, albeit for a short time.
  • In the second case, taking such drugs has no effect. However, one should not think that the absence of inflammation makes the cause of subfebrile condition less serious. On the contrary, serious things such as cancer can be among the non-inflammatory causes of low-grade fever.

As a rule, diseases are rarely found, the only symptom of which is subfebrile condition. In most cases, other symptoms are also present - for example, pain, weakness, sweating, insomnia, dizziness, hypertension or hypotension, pulse disturbances, abnormal gastrointestinal or respiratory symptoms. However, these symptoms are often erased, and the common man is usually unable to determine the diagnosis from them. But for an experienced physician, the picture may be clear.

In addition to your symptoms, you should tell your doctor about any recent activities you have done. For example, did you communicate with animals, what food you ate, whether you traveled to exotic countries, etc. When determining the cause, information about the patient's previous illnesses is also used, because it is quite possible that subfebrile condition is a consequence of the relapse of some long-treated illness.

To establish or clarify the causes of subfebrile condition, usually it is necessary to pass several physiological tests ... First of all, this is a blood test. In the analysis, one should first of all pay attention to such a parameter as the erythrocyte sedimentation rate. An increase in this parameter indicates an inflammatory process or infection. Also important are parameters such as the number of leukocytes, hemoglobin levels.

To detect HIV, hepatitis, special blood tests are required. A urinalysis is also needed, which will help determine if there are inflammatory processes in the urinary tract. At the same time, attention is also paid to the number of leukocytes in the urine, as well as the presence of protein in it. To cut off the likelihood of helminthic invasions, feces are analyzed.

If the analyzes do not allow to unambiguously determine the cause of the anomaly, then studies of the internal organs are carried out. For this, various methods can be used - ultrasound, radiography, computed and magnetic tomography.

A chest X-ray can help detect pulmonary tuberculosis, and an EKG can help detect infective endocarditis. In some cases, a biopsy may be indicated.

Establishing a diagnosis in the case of subfebrile condition can often be complicated by the fact that the patient may have several potential causes of the syndrome at once, but it is not always easy to separate the true causes from the false ones.

What to do if you find yourself or your child with a persistent fever?

Which doctor should I contact with this symptom? The easiest way is to go to a therapist, and he, in turn, can give a referral to specialists - an endocrinologist, an infectious disease specialist, a surgeon, a neurologist, an otolaryngologist, a cardiologist, etc.

Of course, low-grade fever, unlike febrile, does not pose a danger to the body and therefore does not require symptomatic treatment. Treatment in such a case is always aimed at eliminating the hidden causes of the disease. Self-medication, for example, with antibiotics or antipyretics, without a clear understanding of the actions and goals is unacceptable, since it can not only be ineffective and blur the clinical picture, but also lead to the fact that the real ailment will be neglected.

But it does not follow from the insignificance of the symptom that it should be ignored. On the contrary, low-grade fever is a reason to undergo a thorough examination ... This step cannot be postponed until later, reassuring yourself that this syndrome is not dangerous to health. It should be understood that serious problems can be behind such a seemingly insignificant malfunction of the body. published econet.ru .

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