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Low grade fever for three days: Persistent Low-Grade Fever in Kids and Adults: Causes and Treatme

Persistent Low-Grade Fever in Kids and Adults: Causes and Treatme

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Long lasting low-grade fevers can occur with viral or bacterial infections, stress, or certain medications. Other health conditions like thyroid issues or autoimmune diseases can also cause this symptom.

What is a low-grade fever?

A fever is when a person’s body temperature is higher than normal. For most people, normal is roughly 98.6° Fahrenheit (37° Celsius).

“Low-grade” means that the temperature is slightly elevated — between 98.7°F and 100.4°F (37.05°C and 38.0°C) — and lasts for more than 24 hours. Persistent (chronic) fevers are typically defined as fevers lasting more than 10 to 14 days.

A fever can mean a lot of different things, but most low-grade and mild fevers are nothing to worry about. Most often, an increase in body temperature is a normal response to an infection, like a cold or the flu. But there are many other less common causes of a persistent low-grade fever that only a doctor can diagnose.

A fever alone may not be a reason to call a doctor. Yet, there are some situations where you should get medical advice, especially if a fever lasts more than a few days. The presence of a fever can mean different things for adults, infants, and children.


For an adult, a fever isn’t usually a cause for concern unless it goes above 103°F (39.4°C). You should see a doctor if you have a fever higher than this.

If your fever is lower than 103°F, but lasts for more than three days, you should also visit a doctor.

You should seek immediate medical attention if any of these signs or symptoms accompanies a fever:

  • strange rash that rapidly worsens
  • confusion
  • persistent vomiting
  • seizures
  • pain when urinating
  • stiff neck
  • severe headache
  • throat swelling
  • muscle weakness
  • difficulty breathing
  • hallucinations


For infants under 3 months old, even a slightly higher than normal temperature can mean a serious infection.

Call your pediatrician for a low-grade fever if your baby seems unusually irritable, lethargic, or uncomfortable or has diarrhea, a cold, or a cough. In the absence of other symptoms, you should also see a doctor if a fever lasts continuously for more than three days.


If your child is still making eye contact with you, drinking fluids, and playing, then a low-grade fever isn’t likely a cause for alarm. But you should still visit a doctor if a low-grade fever lasts for more than three days.

Also call your child’s pediatrician if your child:

  • is irritable or appears very uncomfortable
  • has poor eye contact with you
  • vomits repeatedly
  • has severe diarrhea
  • has a fever after being in a hot car

Viral infections, like the common cold, are the most common cause of a persistent low-grade fever, but there are other less common causes to consider.

Respiratory infections

Your body naturally raises its body temperature to help kill the bacteria or virus causing an infection. Colds or the flu are caused by viruses. Colds in particular can cause a low-grade fever that lasts more than a few days.

Other symptoms of a cold include:

  • stuffy or runny nose
  • sore throat
  • sneezing
  • cough
  • fatigue
  • lack of appetite

Viral pneumonia and bronchitis are two other types of respiratory infections that can also cause a low-grade fever. Along with a fever, chills, and a sore throat, pneumonia and bronchitis come with a cough that persists for weeks.

In children, it’s common to experience “back-to-back” viral infections. This can make it seem like the fever is lasting longer than it should be.

Treatment for viral infections involves rest and fluids until your body takes care of the infection. You can take acetaminophen for reducing a fever if your symptoms are really bothersome. Fevers are important in helping your body fight off certain infections, so sometimes it’s best to wait it out.

If the infection is more serious, your doctor may prescribe antibiotics, antiviral drugs, or other medications to help treat the infection.

Urinary tract infections (UTIs)

Persistent fever can signal a hidden urinary tract infection in both children and adults. A UTI is caused by a bacterial infection. Other symptoms include pain and burning while urinating, frequent urination, and bloody or dark urine.

A doctor can examine a sample of urine under a microscope to diagnose a UTI. Treatment involves a course of antibiotics.


A low-grade fever can occur about 7 to 10 days after starting a new medication. This is sometimes called drug fever.

Drugs associated with a low-grade fever include:

  • beta-lactam antibiotics, such as cephalosporins and penicillins
  • quinidine
  • procainamide
  • methyldopa
  • phenytoin
  • carbamazepine

If your fever is related to a medication, your doctor may adjust your dosage or recommend a different drug. The fever should disappear once the medication is stopped.

Teething (infants)

Teething usually occurs between 4 and 7 months of age. Teething can occasionally cause mild irritability, crying, and a low-grade fever. If the fever is higher than 101°F, it’s not likely caused by teething and you should bring your infant to see a doctor.


A persistent fever can be caused by chronic, emotional stress. This is called a psychogenic fever. Psychogenic fevers are most common in young women and people with conditions often exacerbated by stress, such as chronic fatigue syndrome and fibromyalgia.

Fever-reducing drugs like acetaminophen don’t actually work against fevers caused by stress. Instead, anti-anxiety drugs are the therapy used to treat a psychogenic fever.


Tuberculosis (TB) is a highly infectious disease caused by a bacterium called Mycobacterium tuberculosis. Though TB is more common in developing countries, thousands of cases are reported in the United States each year.

The bacteria can remain inactive in your body for years and cause no symptoms. When your immune system is weakened, however, TB can become active.

Symptoms of active TB include:

  • coughing up blood or sputum
  • pain with coughing
  • unexplained fatigue
  • fever
  • night sweats

TB can cause a persistent, low-grade fever, especially at night, which can result in night sweats.

A doctor can use a test called the purified protein derivative (PPD) skin test to determine if you’re infected with the TB bacteria. People diagnosed with active TB disease have to take several medications for six to nine months in order to cure the infection.

Autoimmune diseases

Body temperature has been found to be elevated in some people with chronic autoimmune disease, such as multiple sclerosis and rheumatoid arthritis.

In one study, researchers learned that participants with a form of MS called relapsing MS who complained of fatigue also had a low-grade fever.

A low-grade fever is also a common symptom of RA. It’s thought to be caused by inflammation of the joints.

Diagnosing RA and MS can take time and may require multiple lab tests and diagnostic tools. If you’ve already been diagnosed with RA or MS, your doctor will want to first rule out another viral or bacterial infection as the potential cause of your fever.

In case of RA- or MS-related fever, a doctor will likely recommend that you drink plenty of fluids, remove extra layers of clothing, and take a nonsteroidal anti-inflammatory drugs (NSAIDs) or acetaminophen until the fever passes.

Thyroid issues

Subacute thyroiditis is an inflammation of the thyroid gland. It can cause a low-grade fever in some cases. Thyroiditis may be caused by infection, radiation, trauma, autoimmune conditions, or medications.

Other symptoms include:

  • muscle pain
  • fatigue
  • tenderness near the thyroid gland
  • neck pain that often radiates up to the ear

A doctor can diagnose thyroiditis with an examination of the neck and a blood test that measures thyroid hormone levels.


Certain cancers — lymphomas and leukemias in particular — can cause a persistent and unexplained low-grade fever. Keep in mind that a cancer diagnosis is rare and a fever is a nonspecific symptom of cancer. Having a persistent fever doesn’t usually mean you have cancer, but it can alert your doctor to run certain tests.

Other common symptoms of leukemia or lymphoma include:

  • chronic fatigue
  • bone and joint pain
  • enlarged lymph nodes
  • headaches
  • unexplained weight loss
  • night sweats
  • weakness
  • breathlessness
  • loss of appetite

Depending on the type and stage of the cancer, a doctor may recommend a combination of chemotherapy, radiation, surgery, or other treatments.

Fevers will usually go away on their own. Over-the-counter (OTC) medications can help to lower a fever, but sometimes it’s better to ride out a low fever with fluids and rest.

If you decide to take an OTC medication, you can choose between acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, aspirin, and naproxen.

For infants younger than 3 months, call your doctor first before giving them any medication.

For children, acetaminophen and ibuprofen are generally safe for reducing fever. Don’t give aspirin to children under 12 years old who are recovering from flu-like symptoms because it can cause a serious disorder called Reye’s syndrome.

If your child is younger than 12 years of age, talk to your doctor before giving them naproxen.

For teenagers and adults, acetaminophen, ibuprofen, naproxen, and aspirin are generally safe to use according to the instructions on the label.

Shop for acetaminophen and NSAIDs to help lower a fever.

Most low-grade and mild fevers are nothing to worry about.

However, you should call your doctor if you’ve had a fever for more than three days straight, or your fever is accompanied by more troublesome symptoms such as vomiting, chest pain, rash, throat swelling, or a stiff neck.

It’s hard to know when you should call a doctor for a baby or young child. In general, seek medical care if your baby is less than three months old and has any fever at all. If your baby is older than that, you don’t have to see a doctor unless the fever runs above 102°F (38.9°C) or lasts continuously for more than three days.

Continue to monitor your child’s temperature throughout the day. Rectal temperatures are usually the most accurate. Call your pediatrician’s office if you’re not sure what to do.

Persistent low grade fever: Causes and treatments

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Medical News Today only shows you brands and products that we stand behind.

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  • Evaluate ingredients and composition: Do they have the potential to cause harm?
  • Fact-check all health claims: Do they align with the current body of scientific evidence?
  • Assess the brand: Does it operate with integrity and adhere to industry best practices?

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The normal human body temperature is about 98.6°F, but it fluctuates throughout the day. A low grade fever is when the body temperature rises slightly, usually between about 100.5°F and 102.2°F.

The fever is persistent when the body temperature stays in this range for more than 2 weeks.

A fever is commonly a result of the body trying to fight off an infection or another illness. However, some cases are more difficult to diagnose and treat.

Continue reading to learn more about the symptoms, causes, and treatment of a persistent low grade fever.

Share on PinterestIf the body is fighting off an infection, a person may experience a persistent low grade fever.

Some people may hardly notice that they have a low grade fever. However, others may experience various symptoms, including:

  • feeling warm to the touch
  • sweating
  • chills
  • shivering
  • headaches
  • muscle aches
  • dehydration
  • a general feeling of being unwell

A persistent low grade fever is typically a sign that the body is fighting off an infection or another health issue and has raised its temperature to help these efforts.

These underlying issues can include:

Respiratory infections

Respiratory infections can cause a persistent low grade fever. Some of the most common respiratory infections, such as a cold or the flu, may cause a low grade fever that lasts for as long as the body takes to fight off the infection.

Other symptoms that may indicate a respiratory infection include:

  • coughing
  • sneezing
  • a stuffy or runny nose
  • a sore throat
  • chills
  • general fatigue
  • lack of appetite

Many simple respiratory infections do not require treatment, and the symptoms will go away in time.

Urinary tract infections

A urinary tract infection (UTI) may also be the underlying cause of a low grade fever. A UTI is a bacterial infection that occurs when bacteria multiply anywhere in the urinary tract, which includes the bladder, urethra, kidneys, and ureters.

In addition to a low grade fever, the person may experience symptoms such as:

  • pain in the abdomen
  • a burning sensation while peeing
  • frequent urination
  • a constant urge to urinate
  • dark urine

Most UTIs are simple to treat with antibiotics. The doctor may analyze a urine sample to determine the precise type of bacteria causing the infection to ensure that they prescribe the right treatment.

Other infections

Share on PinterestA person should talk to their doctor if they experience any symptoms of infection alongside a fever.

Almost any infection can cause a fever. A fever is one of the body’s natural responses to foreign invaders. The body may keep its core temperature elevated while it is fighting off the infection.

Other sources of infections that may cause a low grade fever include:

  • food poisoning
  • exposure to pathogens from livestock
  • tuberculosis
  • meningitis

Anyone experiencing symptoms of infection alongside a fever should see a doctor if the symptoms do not improve with rest and time.


Some medications can cause many different side effects, which may include a low grade fever. People can check the information on side effects and interactions that comes in the packaging or seek advice from a pharmacist.

As the author of a 2018 review notes, if the medication is the cause, the fever should go away very quickly — typically within 72 hours — once the person stops taking the drug.


Chronic stress may cause a low grade fever. A research paper from 2015 notes that a fever due to stress is most common in young women.

Reducing stress levels may resolve the fever in these cases.


In rare cases, a persistent low grade fever with no known cause may be a sign of cancer.

A persistent fever can be a symptom of leukemia, Hodgkin disease, or non-Hodgkin lymphoma.

The person may also experience other symptoms of cancer, including:

  • persistent fatigue
  • weakness
  • headaches
  • infections
  • lack of appetite
  • excessive bruising or bleeding
  • unexplained weight loss
  • enlarged lymph nodes
  • excessive sweating at night

Many of these symptoms are not unique to cancer, however.

Anyone who experiences these symptoms along with a low grade fever should see a doctor for a diagnosis.

Chronic disorders

Many other chronic disorders may cause symptoms such as a low grade fever, including:

  • thromboembolic disease
  • arthritis
  • lupus
  • gout
  • thyroiditis
  • serum sickness-like reactions
  • serotonin syndrome
  • neuroleptic malignant syndrome

Diagnosing a persistent low grade fever may involve several different tests to eliminate potential causes.

The doctor will generally carry out a physical examination and question the person regarding additional symptoms and whether they have any chronic conditions.

The doctor may also ask about any medications that the person takes so that they can eliminate them as a cause of the fever.

They may order blood tests, such as a complete blood count (CBC), to get an overview of the person’s health. The results may help them decide which other tests, if any, they need to order.

If the doctor suspects that the person has a UTI, they may ask them for a sample of their urine to test.

Share on PinterestOTC drugs may help treat a low grade fever at home.

Treatment for a persistent low grade fever will depend on the cause. For instance, minor infections may not need treatment at all, whereas issues such as cancer require extensive treatment.

To alleviate the symptoms of a low grade fever at home, a person can try over-the-counter (OTC) drugs, such as ibuprofen (Advil) or acetaminophen (Tylenol).

A fever can cause dehydration, so it is vital to drink plenty of water.

It is important to treat a low grade fever in children, who may be more sensitive to temperature changes. Using children’s versions of OTC drugs may help control the fever while waiting to see a doctor.

A persistent low grade fever is a sign of an underlying issue, such as a mild infection or chronic condition. The fever may persist while the person is fighting off the infection.

For the most part, persistent low grade fevers are not a cause for concern. However, it is important to monitor the fever to see whether it gets worse.

Anyone who is concerned about their symptoms or experiences a persistent low grade fever for more than 10 days should see a doctor.


The drugs listed in this article are available online:

  • Ibuprofen
  • Acetaminophen

Subfebrile temperature – what is dangerous? What to do? Where to go in Kazan? MC Health Formula

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 exercise, the temperature may rise slightly

Body temperature is affected by heat, humidity, too warm clothing. In women, there is a slight jump in temperature (by half a degree) on certain days of the menstrual cycle. But it will be a one-time increase. An increase in temperature from 37.2 to 37.9 may be a cause for concern.in a period of more than a month – this is subfebrile temperature.

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

Picture taken from stock.adobe.com in the free section stock.adobe.com/en/free

Causes of subfebrile temperature

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 allergy, arthritis, postinfarction syndrome)
  • Parasites
  • Pathologies of the endocrine system (thyrotoxicosis, severe menopause)
  • Thermoneurosis (vegetative dysfunction affecting heat transfer)

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

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

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

  • overheated
  • under stress
  • when taking certain drugs
  • hereditary factor when a child is born and lives with a fever
  • with activation of the hypothalamus
  • during pregnancy
  • before menstruation.

Such a temperature is not amenable to the action of antipyretic drugs, is easily tolerated and does not have pronounced daily fluctuations.

Examination will help to find out the cause.

Analyzes and studies at subfebrile temperature.

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

Fever for more than two weeks?

Need to submit:

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


  • Chest x-ray (tuberculosis, lung abscess)
  • Electrocardiogram (bacterial endocarditis)
  • Pelvic ultrasound (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.

Therapist of the highest category, cardiologist, gastroenterologist.
Menzhevitskaya Tatyana Ivanovna

causes and what is subfebrile temperature

01/29/2020Updated on 07/14/2021

The normal average body temperature is 36.6°C degrees Celsius. If the deviation on the temperature scale exceeds 0.5 ° C, in one direction or the other, this is not a critical indicator.

However, if the body temperature systematically rises to 37.1°C for no apparent reason, this is a reason to go to the doctor for a detailed clarification of the circumstances.

Usually, subfebrile temperature is called when the mark on the thermometer rises to 38 ° C and stays at this border. And often this is a temperature of 37.1 ° C.

In fact, an increase in body temperature does not occur from scratch.

The leading therapist of the R + Medical Network private clinic will tell you how to recognize low-grade fever and what are the most common reasons for this in medical practice.

Despite the fact that the causes of subfebrile temperature can be very different. Our doctors will still try to detail and convey the most important information to you so that you can pay attention to the hidden symptoms of the pathology in a timely manner and seek medical help. Usually, subfebrile temperature is called when the mark on the thermometer rises to 38 ° C and stays at this border. And often this is a temperature of 37.1 ° C.

What is subfebrile temperature?

Being informed is important. Especially when it comes to your own well-being or the health of loved ones.

So, body temperature can change throughout the day, depending on how you feel, climatic conditions, time of day. Therefore, deviations in the temperature regime of 0.5-1°C are not considered a pathology.

Therefore, if the temperature stays at 37.1°C for a long period, then returns to normal, and then rises again, make an appointment with a specialist. Since the real problem can be detected only after a thorough diagnosis of the body.

Causes of subfebrile temperature can be identified using a complete blood count, fluorography, ultrasound, MRI, etc. Therefore, if the temperature is 37.1 ° C for a long period, then it returns to normal, and then rises again – sign up for a consultation with specialist. Since the real problem can be detected only after a thorough diagnosis of the body.

An increase in temperature is most often an immune reaction to an inflammatory process in the body or an infection.

Thus, the immune system is actively involved in the fight against the “enemy” and signals that a failure has occurred. A virus or a focus of the inflammatory process has appeared in the body.

Therefore, it is very important not to delay the visit to the doctor, but to do it as soon as possible at the first signs of the disease. After all, any disease is always easier to prevent than to treat in the last stages of pathology.

The main causes of subfebrile temperature

The most common causes due to which the body can give temperature alarms are:

  1. Anemia.
  2. Intestinal parasites
  3. Tuberculosis.
  4. AIDS/HIV.
  5. Toxoplasmosis, sepsis.
  6. Oncological diseases.
  7. Diseases of the thyroid gland.
  8. Viral hepatitis, intestinal infection.
  9. Autoimmune diseases (allergies, arthritis, ulcerative colitis, rheumatism).
  10. Hormonal disorders (in pregnant women, as a variant of the norm).

By the way, the causes of a temperature of 37 ° C in women may well lie in the natural ovulation period, so if you are approaching or having your period, you should not worry about this.

Subfebrile temperature in a child. What to do?

If a teenager or young child has a subfebrile temperature, first and foremost, make sure that this is not a “temperature tail” (the result of a cold or a viral illness).

Many parents start to panic when their child has a temperature of 37°C, but at the same time they forget that the child has just recently had SARS, flu or tonsillitis.

After ARVI, a child may have subfebrile temperature for 5-14 days. And that would be the norm.

However, if the child has a subfebrile temperature and he cannot explain his condition to you, it is important to contact a competent doctor who will diagnose and determine the exact cause of the temperature increase for further correct treatment.

Normal temperature range for people of different ages


Age 90 224

0-2 years

3-11 years

11-65 years old

over 65 years old 03





90 233







36.6°C-38.0°C 36.6°C-38.0°C



Tympanic 0233

36.1°C-37.7 °С


35. 8°С-37.5°С

Internal organs 9000 3

36.3°С- 37.7°C




These temperature ranges can be observed in most people of all ages. Balancing these boundaries remains the norm if the temperature changes under the influence of external factors or characteristics of the organism (this should be clarified with the doctor).

However, if low-grade fever causes discomfort or is accompanied by symptoms of an unknown etiology, your task is to find the cause as soon as possible and begin effective treatment.

R+Medical Network premium class private clinic in Goloseevsky and Pechersky districts of Kyiv is distinguished by the fact that we provide patients with an integrated approach to both diagnosis and treatment of diseases.

We are not satisfied with a single indicator of tests, we are interested in a detailed analysis of the root cause of subfebrile temperature and its immediate elimination .