Subfebrile temperature: what does it mean

Health Tips

However, if nothing hurts you, you most likely will not know that the temperature is elevated: you don’t measure it in the morning just in case? Well, except when planning a pregnancy. Let’s say you have just that case. Well, or for a moment they felt unwell, measured – and there 37.2. Or they got sick – the cough went away, the runny nose went away, but the temperature remained. Is it time to panic?

What is the norm

36.6 is considered a normal indicator of human body temperature. However, this figure can change during the day depending on biorhythms, physical activity, hormonal levels, and emotional state. Thus, the range within which the temperature in a healthy person can fluctuate is 35.5–37.4. Such physiological fluctuations are considered normal, unless, of course, the temperature rises once and for a short time. Therefore, you should not grab a thermometer after a morning run, after a trip to the subway at rush hour, after a quarrel with your husband, and even after eating: the indicators will be biased.

Subfebrile temperature is a stable increase to 37.0-37.5, which persists for many days. In this case, a person may feel unwell, but often subfebrile condition goes unnoticed, since it is not accompanied by any other symptoms of the disease. Diagnosing the cause of subfebrile temperature is quite difficult, since there are a lot of conditions that cause it.

The child has

The causes of low-grade fever in adults and children are the same, with a few exceptions. In children, a stable increase in temperature can be observed during the period of active growth from 8 to 14 years. In babies up to a year, subfebrile condition is also associated with BCG vaccination. Many parents believe that if the child is alert at the same time, he has no problems with appetite and sleep, then the temperature increase can be ignored. This is a dangerous delusion! The child should be shown to the pediatrician: subfebrile temperature can be a symptom of tonsillitis, adenoiditis, allergic conditions, helminthiasis (worms) and other diseases that do not always manifest themselves clearly. Do not be afraid in advance, but it can even be pyelonephritis, ulcerative colitis, Crohn’s disease, acute or chronic hepatitis …


It happens that subfebrile condition persists after acute respiratory viral infections – and then chronic processes must be excluded: for example, tonsillitis or even pneumonia (it does not necessarily manifest itself with extreme temperature).

If low-grade fever is of an infectious nature (any inflammation, viral or bacterial infection, parasitic invasion), then you most likely will not miss it: against the background of infections, the temperature is usually rather poorly tolerated. Subfebrile condition associated with infections can be removed by taking an antipyretic. This is the so-called aspirin test, which can be used in diagnosis: with a positive reaction to the drug, it can almost certainly be argued that the cause of low-grade fever is an infection.

Hormonal causes

Often the cause of a stable and long-term increase in temperature is hormonal changes. In particular, dysfunction of the thyroid gland is called hyperthyroidism.

As we have already said, a hormonal surge can provoke an increase in temperature in adolescents at puberty. Subfebrile condition is often encountered by women in menopause or in the first trimester of pregnancy. But by themselves, these conditions – puberty, pregnancy and menopause – do not relieve responsibility. Most likely, of course, nothing terrible. However, in adolescence and in the first trimester of pregnancy, “37 with a tail” can be a symptom of infectious diseases and parasitic invasions: helminthiasis, brucellosis, various viral infections (cytomegalovirus, herpetic, toxoplasmosis, tuberculosis, HIV).

And in the menopause, the risk of developing oncology increases, often it is a small temperature that is the first sign of cancer development – this is how the body reacts to toxins and metabolic products that cancer cells secrete.

Allergy and nerves

Allergic reactions can also be accompanied by low-grade fever. But to be accompanied. Temperature is rarely the only symptom of an allergy. But if you sneeze while dismantling bookcases, and at the same time you have 37.3, this does not mean that a cold has superimposed on an allergy. Try taking an antihistamine.

Violation of the nervous system, in particular, disruption of the thermoregulatory centers of the brain, is another cause of fever. It can be recognized at home using the same aspirin test: if the temperature does not go astray, then you need to see a neurologist.

What to do

If you watch 37.2 on a thermometer day after day, you need to visit a general practitioner. He will prescribe a certain range of examinations – a urine test, a blood test, an X-ray of the lungs and paranasal sinuses, an ECG, an ultrasound of the internal organs … And only by eliminating all possible causes one after another, you can finally calm down. And when you worry, the temperature rises – have you noticed?

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