What are the most frequent reasons for a low-grade fever lasting more than a week. How can you identify the underlying cause of a persistent low-grade fever. When should you seek medical attention for a prolonged low-grade fever.

Understanding Low-Grade Fever: What It Is and When to Be Concerned

A low-grade fever is typically defined as a body temperature between 37.5°C and 38.3°C (99.5°F to 100.9°F). While it’s often not a cause for immediate alarm, a persistent low-grade fever lasting more than a week can be a sign of an underlying health issue. Is a low-grade fever always a cause for concern? Not necessarily, but it’s important to monitor your symptoms and consult a healthcare professional if the fever persists or is accompanied by other troubling signs.

Key Characteristics of Low-Grade Fever

• Temperature range: 37.5°C to 38.3°C (99.5°F to 100.9°F)
• Duration: Lasting more than a few days
• Often accompanied by mild symptoms like fatigue or body aches
• May fluctuate throughout the day

COVID-19: A Common Culprit Behind Persistent Low-Grade Fever

In the current global health landscape, COVID-19 remains a significant cause of prolonged low-grade fever. Can COVID-19 cause a fever that lasts for weeks? Yes, in some cases, particularly with long COVID, individuals may experience a persistent low-grade fever as part of their symptoms. It’s crucial to consider COVID-19 as a potential cause, especially if you’ve been exposed or have other typical symptoms such as cough, fatigue, or loss of taste and smell.

COVID-19 and Fever: What to Watch For

• Fever may be accompanied by respiratory symptoms
• Loss of taste or smell is a distinctive sign
• Fatigue and body aches are common
• Testing is crucial for accurate diagnosis

Pneumonia: A Serious Condition That Can Cause Prolonged Low-Grade Fever

Pneumonia, an infection that inflames the air sacs in one or both lungs, can manifest as a persistent low-grade fever. Does pneumonia always cause a high fever? Not necessarily. While some cases of pneumonia result in high fevers, others, especially in older adults or those with weakened immune systems, may present with a low-grade fever that persists for an extended period.

Recognizing Pneumonia Symptoms

1. Persistent cough, often with phlegm
2. Chest pain when breathing or coughing
3. Shortness of breath
4. Fatigue and weakness
5. Low-grade fever that may last for weeks

Urinary Tract Infections: An Often Overlooked Cause of Low-Grade Fever

Urinary tract infections (UTIs) are a common cause of low-grade fever, especially in women and older adults. Can a UTI cause a persistent low-grade fever? Indeed, if left untreated, a UTI can lead to a prolonged low-grade fever as the body fights the infection. It’s important to note that not all UTIs present with typical symptoms like burning during urination, making the fever a key indicator.

UTI Symptoms to Be Aware Of

• Frequent or urgent need to urinate
• Burning sensation during urination
• Cloudy or strong-smelling urine
• Pelvic pain in women
• Low-grade fever that may persist

Autoimmune Disorders: When Your Body’s Defense System Causes Fever

Autoimmune disorders occur when the body’s immune system mistakenly attacks healthy cells. Many of these conditions can cause a persistent low-grade fever as part of their symptom profile. How do autoimmune disorders lead to fever? The ongoing inflammation associated with these conditions can trigger the body’s temperature regulation system, resulting in a low-grade fever that may last for weeks or even months.

Common Autoimmune Disorders Associated with Low-Grade Fever

1. Rheumatoid Arthritis
2. Lupus
3. Sjögren’s Syndrome
4. Multiple Sclerosis
5. Inflammatory Bowel Disease

Tuberculosis: A Serious Infection with Subtle Fever Symptoms

Tuberculosis (TB) is a bacterial infection that primarily affects the lungs but can impact other parts of the body as well. Can tuberculosis cause a low-grade fever for weeks? Yes, one of the hallmark symptoms of TB is a persistent low-grade fever that may last for weeks or even months. This fever is often accompanied by night sweats and unexplained weight loss.

Tuberculosis Symptoms to Watch For

• Persistent cough lasting more than three weeks
• Coughing up blood or sputum
• Chest pain
• Unexplained weight loss
• Night sweats
• Low-grade fever that persists

Endocarditis: When Heart Infection Leads to Prolonged Fever

Endocarditis is an infection of the inner lining of the heart chambers and valves. This serious condition can manifest as a persistent low-grade fever, often accompanied by other symptoms. Why does endocarditis cause a prolonged fever? The ongoing infection in the heart triggers an immune response, leading to a persistent low-grade fever as the body attempts to fight off the infection.

Key Signs of Endocarditis

1. Persistent low-grade fever
2. Fatigue and weakness
3. Shortness of breath
4. Heart murmur
5. Joint and muscle pain
6. Night sweats

Malignancies: When Cancer Causes Unexplained Fever

Various types of cancer can cause a persistent low-grade fever, often referred to as a fever of unknown origin when other causes have been ruled out. How does cancer lead to fever? Certain cancers, particularly blood cancers like lymphoma and leukemia, can trigger the release of substances that affect the body’s temperature regulation. Additionally, some solid tumors can cause fever as they grow and interact with the immune system.

Cancer Types Associated with Persistent Low-Grade Fever

• Lymphoma
• Leukemia
• Kidney cancer
• Liver cancer
• Colon cancer

Medication-Induced Fever: When Treatment Becomes the Cause

In some cases, the very medications intended to treat a condition can lead to a persistent low-grade fever. This phenomenon, known as drug fever, can occur with various types of medications. Can antibiotics cause a prolonged low-grade fever? Yes, certain antibiotics, along with other medications, can trigger a fever as a side effect. It’s crucial to review all medications with a healthcare provider if you’re experiencing an unexplained persistent fever.

Medications That May Cause Drug Fever

1. Antibiotics (e.g., beta-lactams, sulfonamides)
2. Anticonvulsants
3. Antiarrhythmics
4. Certain blood pressure medications
5. Some anti-inflammatory drugs

Understanding the potential causes of a persistent low-grade fever is crucial for proper diagnosis and treatment. While this article covers eight common causes, it’s important to remember that there can be other reasons for prolonged low-grade fever. Always consult with a healthcare professional if you’re experiencing a fever that lasts more than a week or is accompanied by other concerning symptoms.

Diagnostic Approaches for Persistent Low-Grade Fever

When faced with a persistent low-grade fever, healthcare providers employ a range of diagnostic tools to identify the underlying cause. What are the common diagnostic tests for unexplained fever? Typically, the diagnostic process begins with a thorough medical history and physical examination, followed by various tests tailored to the suspected causes.

Common Diagnostic Tests for Persistent Low-Grade Fever

• Complete blood count (CBC)
• C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) tests
• Blood cultures
• Urinalysis and urine culture
• Chest X-ray or CT scan
• Autoimmune panels
• Tuberculosis tests (e.g., QuantiFERON-TB Gold)

In some cases, more specialized tests may be necessary, such as echocardiograms for suspected endocarditis or biopsies if a malignancy is suspected. The key is to work closely with your healthcare provider to determine the most appropriate diagnostic approach based on your specific symptoms and medical history.

Treatment Strategies for Persistent Low-Grade Fever

The treatment for a persistent low-grade fever depends entirely on its underlying cause. How is a prolonged low-grade fever typically treated? In many cases, addressing the root cause will resolve the fever. However, symptomatic treatment may be recommended to improve comfort while the underlying condition is being addressed.

General Treatment Approaches

1. Antibiotics for bacterial infections
2. Antiviral medications for certain viral infections
3. Immunosuppressants for autoimmune disorders
4. Targeted therapies for specific conditions (e.g., chemotherapy for cancer)
5. Over-the-counter fever reducers for symptomatic relief

It’s crucial to follow your healthcare provider’s recommendations and complete any prescribed treatments, even if your fever resolves before finishing the course of medication. This approach helps prevent recurrence and potential complications.

When to Seek Immediate Medical Attention

While a low-grade fever itself is often not an emergency, certain accompanying symptoms or circumstances warrant immediate medical attention. When should you go to the emergency room for a persistent low-grade fever? If you experience any of the following in conjunction with your fever, seek immediate medical care:

• Severe headache or neck stiffness
• Confusion or altered mental state
• Difficulty breathing or chest pain
• Severe abdominal pain
• Uncontrolled vomiting or diarrhea
• Seizures
• Sudden onset of fever in an immunocompromised individual

Remember, while a persistent low-grade fever can be concerning, it’s often a sign that your body is fighting an underlying condition. By working closely with your healthcare provider and staying vigilant about your symptoms, you can identify the cause and receive appropriate treatment. Don’t hesitate to seek medical advice if you’re unsure about the severity of your condition or if your symptoms worsen over time.

Low grade fever for 3 weeks that isn’t an infection – Pre-Diagnosis, Signs & Symptoms – Cancer Chat

18/M

I’ve been suffering from a low grade fever of around 37.3C to 37.5C for the past few weeks.  I’ve been to a GP and at first he told me it was anxiety and gave me some meds. I didn’t get much better so I went to the GP again, who gave me some different meds, and after taking those, everything but the fever was pretty much fixed, aside from some occasional aching and headaches. I went to the GP again today, and he tweaked the meds again, but still doesn’t really know why I still have a fever.  I had a CBC blood test, and the results came out fine, and the GP says the blood test shows I don’t have inflammation.

I’ve taken even more meds and the fever still hasn’t broken yet, it hasn’t gotten any worse or any better.  I also occasionally feel light headed, and my muscles often twitch, but that could be because of the medicine that’s supposed to make you fatigued.

I’m getting really worried becuase I still don’t know where the fever is coming from, all I know is it isn’t from an infection, which is freaking me out even more because i’d rather get an infection since they’re easy to treat.   I’m thinking that i’ve gotten cancer and I don’t know what to do.  I don’t know if I should schedule another appointment with the GP or like get a full body MRI scan to make sure I don’t have any tumors.

• I have a fever on and off for over 3 weeks now. It goes up to around 37.8 and wakes me from my sleep making me feel hot and sweaty. I have anxiety and am worried sick. All my bloods have come back normal which I dont know is a good or bad thing 🙁 

• It’s kinda comforting to know that i’m not alone in my suffering.  I used to have trouble sleeping too until my doctor gave me meds that had a side effect of making me tired, maybe ask your doctor for something similar.   I just went to my GP today for an X-ray on my lung and a urine test, still waiting for the results.  My GP says the next step would be further blood testing, specifically for auto-immune issues.

  Let’s hope we both recover soon.

• I wouldnt call under 37.5 a fever though. Does yours ever go higher than this? My doctor said she would be more concerned if mine was over 38 but last night mine went up to 38 and I was shaking like I had chills. Really finding it hard to not let my anxiety take over me about this 

• I’ve had it go up to 37.8 before, and I had flu-like symptoms along with it.  My GP says anything over 37.3 is a low fever tho.  And the anxiety is getting pretty bad for me too, really considering admitting myself to a hospital for an MRI or more.

• I have health anxiety and know how you feel. Staying off google is so difficult for me. I dont know why I do it when it makes me worried sick! Glad you have had an xray, I hope your results are clear. I am going to go back to my GP and push for tests

• Hi Carl

   

  Did you find out what was causing your low grade fever? I have this for more than a month now and i dont have other symptoms apart from anxiety.. hope you can get back to me

  thanks

• 25/M

  Hi All, 

  I am dealing with the same thing. I have a fever and my skin feels very warm. I am waking up at around 5.30am every morning and struggle to get back to sleep. I also have been having mild headaches. 

  Got bloods done a few weeks back and came back normal. I dont have a high temp but my skin just feels consistently warm. 

  Not sure what to do next. If it continues I will need to get an MRI scan done I think. 

  Would be great to know the outcome of the above situations too. Thanks!

• I have had a fever of 38+ that comes and goes for almost 3 months now. had blood tests done which showed raised LDH and protein but everything else normal. Currently waiting on a CT scan appointment and had some other bloods done which came back satisfactory 

  What was your outcome?

• Hi,

   

  I hope you’re feeling better now. Did you find out the reason for your fever. I am having the same symptoms are I am proper stressed.

   

  thanks

• Hii

  im still the same blood tests came back fine and gp said with her termometer i dont have a fever…of course i dont because she was barely touching my ear lol when taking the temp. Im calling them back today to ask to send me to a neurologist as i also had loads twitches adnd sometimes my ear gets numb and thinking maybe i have ms as i have seen that can cause a low grade fever. 
  mine started in march and it is still going somedays are good where temp will be 37.3/4 but then agai it will start like today woke up with 37.8 temp… hows ur temp? Above 37.6 is a low grade fever.. xx

10 Reasons You Have a Fever

1. Systemic

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2. Fever

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Fever may spike for a variety of reasons—some not serious, others more so.

Written by

Petrina Craine, MD.

Assistant Clinical Professor of Emergency Medicine, Columbia University

Last updated March 22, 2022

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Symptoms

Causes

Next Steps

Treatment

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Written by

Petrina Craine, MD.

Assistant Clinical Professor of Emergency Medicine, Columbia University

Last updated March 22, 2022

Fever quiz

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8 most common causes

Coronavirus

Strep Throat

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Sinusitis

Mononucleosis

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Viral Gastroenteritis

Pneumonia

Acute URI

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What’s a fever?

When your body temperature rises above normal, you have a fever. Normal varies among us, but is about 97°F to 99°F. But body temperature can fluctuate throughout the day, when exercising, during menstrual cycles, and for other reasons unrelated to being sick.

A fever occurs when the hypothalamus (a sensor area of our brain) increases our body temperature, usually to help “burn off” a viral or bacterial infection. A fever is often accompanied by other symptoms like feeling flushed, sweating, getting chills, muscle aches, and fatigue.

Illnesses that can cause a fever range from the common cold and sore throat to more serious conditions like pneumonia and appendicitis. A persistent low-grade fever may be the first sign of diseases such as lupus or certain cancers like lymphoma.

Fever is different from hyperthermia. Hyperthermia is when the body can no longer regulate its temperature. Temperature can rise to over 104°F. It’s like your body’s internal thermostat has stopped working and the environmental temperature has taken over. Hyperthermia is a life-threatening emergency—go to the emergency room immediately for further care.

Fever can usually be treated with over-the-counter fever reducers like acetaminophen (Tylenol) or ibuprofen (Advil or Motrin).

Causes

1. Mononucleosis

Symptoms

• Fever
• Sore throat
• Fatigue
• Swollen lymph nodes

Mononucleosis, or mono, is a highly contagious viral infection typically caused by the Epstein-Barr virus. Though it can be caused by other viruses (such as cytomegalovirus). Mono spreads through saliva, which is why it’s often called “the kissing disease. ” But it can also be spread by sneezing, coughing, and sharing things like water bottles.

It’s a viral infection, so antibiotics won’t treat it. Symptoms can last as long as 1 to 2 months. Try to get plenty of rest (you’ll be tired) and take it easy. Drink lots of fluids and take ibuprofen (Advil) or acetaminophen (Tylenol) to bring down your fever.

2. Influenza (flu)

Symptoms:

• Fever
• Cough
• Congestion
• Headache
• Body aches
• Nausea, vomiting, diarrhea (especially in young children)

The flu is an infection of the respiratory tract (e.g.,your lungs, nose, and mouth) caused by the influenza virus. There are different types of flu viruses, which is why it’s important to get a flu shot every year.

Most people who get the flu recover in a few days. But some develop complications like pneumonia. This can be life-threatening, especially for the elderly or people with compromised immune systems.

If you are at risk of complications, call your doctor right away or go to urgent care. You may be prescribed an antiviral medication, which can reduce the number of days you are sick and your risk of complications.

Otherwise, treat your symptoms as needed. You can take over-the-counter pain relievers like acetaminophen or ibuprofen. Get plenty of rest and drink lots of fluids.

It’s important to see a doctor if symptoms don’t get better, you can’t drink enough fluids, or your fever lasts for longer than 3 to 5 days.

Dr. Rx

Medicines are often mixed with other medicines, such as over-the-counter medicines for the common cold and for the flu. Unintentional overdoses can and do happen from mixing multiple combinations of these medicines. It is best to choose one fever-reducing medicine to take during your illness. —Dr. Petrina Craine

3. Pneumonia

Symptoms

• Fever
• Cough (which may also produce mucus/phlegm)
• Trouble breathing or increased breathing rate
• Fatigue
• Chest pain
• Nausea, vomiting, loss of appetite, and diarrhea (especially in younger children)
• Confusion (especially in the elderly)

Pneumonia is an infection in your lungs. It’s most commonly caused by viruses and bacteria. The infection irritates the air sacs. They fill with pus and other fluids, making it more difficult to breathe. Colds, bronchitis, influenza, and other respiratory infections can lead to pneumonia if bacteria starts to breed in your lungs.

Pneumonia can be life-threatening, especially to the elderly or people with compromised immune systems, which is why immediate diagnosis and treatment is essential.

Pneumonia is often diagnosed with a chest x-ray. Pneumonia caused by bacteria can be treated with antibiotics.

You may have to be admitted to the hospital if you have low oxygen levels, severe dehydration, or other complications.

4. Common cold

Symptoms

• Runny nose
• Cough and congestion
• Low fever
• Fatigue
• Body aches (usually mild)

A common cold is a viral infection of the respiratory tract (usually just your nose and mouth). Many types of viruses can give you a cold, but rhinoviruses are a common culprit.

Most people have relatively mild symptoms and recover in a few days. Over-the-counter medications, such as decongestants (such as pseudoepinephrine) and natural foods like honey (in ages 2 and older), may relieve symptoms like congestion, cough, and sore throat. Resting and drinking a lot of fluids can also help you feel better.

5. Sinusitis

Symptoms

• Fever
• Runny nose
• Congestion
• Facial pain or pressure
• Headache
• Cough that may produce mucus
• Foul-smelling breath or taste in mouth

The sinuses are small air pockets in your forehead, nose, cheekbones, and in between your eyes. Normally they produce thin mucus to help trap foreign materials. When infected with viruses or bacteria, sinuses produce more fluid and it can get thicker—causing blockages. That can lead to infection, called sinusitis. Most sinus infections are caused by viruses, so antibiotics won’t help treat symptoms. If your symptoms last longer than 10 days or get worse after 5 to 7 days, you may have bacterial sinusitis and will need to see a doctor who may prescribe antibiotics.  

Over-the-counter decongestants (such as pseudoephedrine) should be used with caution. Taking them for more than 3 days increases the risk of the congestion coming back. Sometimes even worse than before. Monitor symptoms and make sure to drink lots of fluids to help relieve pressure.

6. Strep throat

Symptoms

• Fever
• Sore throat
• Painful swallowing
• Tender lymph nodes
• Swollen, red tonsils

Strep throat is a throat infection caused by a bacteria called group A Streptococcus. Strep throat is contagious and more common in children than adults. A hallmark symptom is a very sore throat that may make eating, talking, or swallowing difficult. Sometimes strep throat is associated with a rash that looks like sandpaper—it’s known as scarlet fever.

Strep throat is diagnosed with a test and is treated with antibiotics. If left untreated, it can turn into a more serious illness such as rheumatic fever. Antibiotics may make you feel better in the next few days but it’s important to take the antibiotics for the full course prescribed.

7. Gastroenteritis (stomach flu)

Symptoms

• Nausea or vomiting
• Stomach pain
• Diarrhea
• Chills or sweating
• Fever

Gastroenteritis, or stomach flu, is inflammation of your gastrointestinal (GI) organs, like your stomach and intestines. It is usually caused by infection with a contagious virus, such as the rotavirus or norovirus. Most people recover in a few days at home.

It is very important to drink fluids as the body can lose a lot of water and electrolytes from throwing up or diarrhea. If you think you’re dehydrated or cannot keep any foods or liquids down, talk to your doctor. Your doctor may recommend hospitalization for monitoring and IV fluids for rehydration.

Also, gastroenteritis can sometimes mimic other more serious conditions such as appendicitis, which often has symptoms like fever, nausea and vomiting, and belly pain. Call your doctor when in doubt about the cause of your symptoms.

8. COVID-19

Symptoms

• Fever
• Loss of taste or smell
• Cough or congestion, which may produce mucus
• Runny nose
• Nausea, vomiting, or diarrhea
• Chest pain
• Fatigue
• Body aches
• Chills
• Headache
• Low oxygen levels on a pulse oximeter (oxygen measuring device)

COVID-19 is a new, highly contagious virus caused by a coronavirus, specifically the SARS-CoV-19. This virus infects the respiratory tract (including your nose, throat, sinuses, and lungs). But it can also affect other organs including the brain, blood vessels, and the skin.

Symptoms are very similar to those of the flu. Sometimes, COVID-19 begins with mild symptoms that become life-threatening.

Rest and drinking lots of fluids can be important in treating symptoms and feeling better for people with mild cases of COVID-19. If you suspect COVID-19, monitor the progression of your symptoms and keep your doctor updated about your symptoms.

Your doctor will recommend additional at-home treatment plans, which may include over-the-counter medication, oxygen monitoring devices, or prescription medication, like an inhaler. They can also advise you when to go to the hospital if your symptoms worsen.

9. Cancer

Symptoms

• Fever that comes and goes
• Unexplained weight loss
• Easily bruised skin
• Swollen lymph nodes
• Chills
• Fatigue

Cancer can cause a persistent low-grade fever, as well as chills. This is especially true for certain blood cancers like leukemia, lymphoma, or myeloma. See a doctor if a fever doesn’t break, if you have a continual low-grade fever or a low-grade fever that seems to come and go.

Cancer may cause other symptoms, such as unexplained weight loss, swollen lymph glands, or fatigue regardless of how much sleep you’ve been getting. Blood cancers may also cause easily bruised skin or bleeding gums.

Treatment depends on the type of cancer and how far it has progressed. Treatment may include chemotherapy, radiation, and/or surgery.

10. Autoimmune disease

Symptoms

• Fatigue
• Fever (usually low-grade)
• Swollen glands
• Joint pain
• Digestive issues
• Skin or hair changes

Various autoimmune diseases such as lupus and rheumatoid arthritis may cause a low-grade fever. Autoimmune disorders can interfere with daily life and can make it hard to manage daily tasks without pain. They can also make you feel exhausted, depressed, and lower your quality of life.

Autoimmune disorders can have a range of symptoms and can be complicated to diagnose. Often, diagnosis is made by ruling out other causes. Treatment can include symptom management, medication, and immunotherapy.

Other possible causes

A number of conditions may also cause fever. These include:

• Diseases transmitted by ticks like Lyme disease
• Appendicitis
• Urinary tract infection (fever is usually a sign that the upper urinary tract—like the kidneys—is affected)
• Extreme sunburn (rare)
• Food poisoning (usually a mild fever occurs if any)
• Blood clots (rare)
• Tuberculosis

Pro Tip

Knowing the measured number on the thermometer and how the temperature was taken (e.g. from the mouth or from the forehead) are both incredibly helpful tidbits to tell your doctor when caring for someone with a fever. It’s also important to let your doctor know if any medicines were given to help reduce fever and what time they were taken. —Dr. Craine

When to call the doctor or visit the ER

• You have a moderate to severe fever—usually 102°F and greater.
• You have a fever that has been persistent (greater than 3 to 5 days).
• You have a weakened immune system (elderly adults, people with cancer, people on medications that suppress the immune system, people with chronic conditions like diabetes, etc.). Even an elevated temperature above 100°F could be the first sign of illness.
• You recently had surgery or some other procedure.
• You are pregnant.
• You think you may have been exposed to a tick.

The list above may also mean a trip to the ER is necessary. You should also visit the ER for the following:

• You have extreme pain (including neck, head, and back pain).
• You’re feeling confused or having hallucinations.
• You’re vomiting blood or you have bloody stool.
• You have trouble breathing.
• You’re experiencing severe hives or swelling.
• You have a seizure.
• You are having trouble eating and drinking enough to stay hydrated.

When to call the pediatrician

It’s important to get an accurate temperature reading in children, especially infants. Ear and forehead thermometers provide less accurate readings than oral and rectal thermometers.

Call the pediatrician in the following circumstances:

• Fever doesn’t break even with fever-reducing medications.
• Child or toddler isn’t eating or drinking.
• Child or toddler is inconsolable and seems to be in pain.
• You have an infant between 3 and 6 months with a fever greater than 102°F.

If your infant is younger than 3 months, the American Academy of Pediatrics advises calling your pediatrician or going to an ER immediately if your infant has a fever greater than 100.4°F, even if they have no other symptoms. Infants who are less than 1 month old or have other risk factors for serious illness should see a doctor for any fever.

Pro Tip

Sometimes patients are especially fearful of a fever, especially a high one. They feel that the fever will cause a seizure in anyone. That’s fortunately not true. Febrile seizures—as they are called—are more likely to occur in children than adults. But only about 2%–5% of children with fever will ever experience a seizure from it. —Dr. Craine

Treatment

At-home care

• Bathe or shower with lukewarm water. The “old wives’ tale” about only using cold water is not necessary and may make you feel even worse.
• Keep the room temperature at a comfortable level.
• Drink plenty of fluids.
• Take fever-reducing medicines like ibuprofen or acetaminophen.

Other treatment options

• Medical testing to help identify the cause of fever.
• IV hydration.
• Hospital monitoring.
• Prescription medication or additional treatments to treat the underlying cause of fever.

Fever can make anyone feel awful, but its health effects are often temporary and short-lived. Setting self-care goals such as staying hydrated and getting adequate rest are often all that most people need to do to help support their bodies during this time. Thankfully, most people with fever don’t experience long-term health complications from it.

Petrina Craine, MD.

Assistant Clinical Professor of Emergency Medicine, Columbia University

Dr. Petrina Craine is an emergency medicine physician who hails from Memphis, TN. After graduating as valedictorian of her high school, she moved to Durham, NC to pursue a degree in Biology and a certificate in Global Health. After college, she returned to her birthplace to attend the University of Tennessee Health Science Center College of Medicine. She successfully completed her medical degree a…

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Subfebrile temperature: physiological and pathological causes

1. Daily body temperature fluctuations
2. Subfebrile condition during physical exertion and stress
3. Fever and menstruation
4. Subfebrile temperature when taking medications
5. Pathological causes of subfebrile condition
6. Diagnosis and treatment
7. Thermoneurosis

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Body temperature is an important indicator of health. It is known that the organs and tissues of our body can function normally only in a certain temperature range. The danger is both a significant increase (hyperthermia) and low body temperature.

The human body has the ability to self-regulate. This also applies to body temperature, which, without any external influences, is maintained at approximately the same level. The hypothalamus is responsible for this function.

Temperature occurs due to the production of heat by organs and tissues. However, it is not uniform. Muscles, the liver and kidneys generate the most heat, while superficial tissues, especially the skin, have higher heat transfer. Of all the organs, only the brain differs in temperature constancy: its temperature is always the same.
Subfebrile condition is an increase in temperature from 37.2 to 37.9 ° C. Experts emphasize that this phenomenon is not necessarily due to pathology. The body is constantly undergoing many physiological processes that can cause an increase in body temperature.

Daily body temperature fluctuations

In the absence of pathology, the difference between morning and evening temperatures reaches 0.5–1.0 °C. Daily fluctuations in internal temperature occur in accordance with the so-called “biological clock”.
If you take the temperature in the early morning hours, immediately after sleep, its value will be in the range from 35.6 to 36.1 ° C, and this is completely normal. During the day, with increased physical activity, the thermometer shows the usual value in the region of 36.6 ° C. By evening, the temperature in healthy people tends to rise slightly. This usually happens between 4:00 pm and 6:00 pm. For some, the fluctuations are quite significant: in the evening, the temperature reaches the borderline mark of 37.2 ° C.

Physiological low-grade fever is easily tolerated and does not require antipyretics.

Subfebrile condition during physical exertion and stress

If you are in the heat or in a very heated room, dressed too warmly, this affects the body temperature, causing it to rise. Subfebrile condition during overheating is short-term. As soon as the ambient temperature returns to normal, the body temperature also returns to normal.

The same happens during physical activity, which activates all processes, accelerates blood circulation. In heat and stress, the internal temperature can rise by two or more degrees. In this case, the skin, on the contrary, cools due to the release of sweat, as the hypothalamus seeks to establish a balance between the formation and release of heat.

Fever and menstruation

In women, body temperature is correlated with the menstrual cycle and hormonal fluctuations. During ovulation, manifestations of subfebrile condition can be observed, which persist until the onset of menstruation. This is an individual physiological norm. In some women, subfebrile condition is accompanied by pregnancy. Most often this occurs in the first trimester, due to increased production of progesterone. This hormone affects the thermoregulatory center in the brain. That is why in pregnant women the temperature can rise to 37.2-37.4 ° C. According to statistics, this phenomenon occurs in 3-5% of women. Most often, subfebrile condition during pregnancy is accompanied by drowsiness, fatigue, changes in appetite. By 12-14 weeks the situation is normal.

If subfebrile temperature during pregnancy is not associated with an infection, the increase does not adversely affect the development of the fetus. If there are complaints, alarming symptoms, a pregnant woman should undergo an examination to determine the cause of poor health.

Subfebrile temperature when taking medications

Subfebrile condition of medicinal etiology is a common phenomenon. Many drugs provoke an increase in temperature. This list includes barbiturates, anti-tuberculosis drugs, penicillion drugs, cephalosporins, atropine, heparin. The temperature may rise if the person is being treated with antibiotics or chemotherapy drugs. In the first case, this is due to the production of endotoxins, in the second case, it is due to the decay of tumor cells.

The body can also react with subfebrile condition to the introduction of a vaccine, invasive medical procedures (dental treatment, prosthetics).

As a rule, such an adverse reaction occurs at the beginning of treatment, occasionally – after a few days or weeks. In addition to fever, the patient is faced with other signs of hypersensitivity to the components of the remedy. It can be a rash, itching, dizziness, nausea.

Subfebrile condition of medicinal origin disappears within two days after discontinuation of the drug.

Pathological causes of subfebrile condition

Everyone knows that an increase in body temperature accompanies various diseases and pathological conditions. The same applies to subfebrile condition. If it persists for two or more weeks, you should consult a doctor, even if the person is not bothered by anything.

Among the pathological causes of subfebrile temperature, there are:

• infectious lesions;
• foci of chronic inflammation in organs and tissues;
• oncological processes;
• autoimmune diseases;
• parasitic infections;
• hormonal disorders;
• allergic reactions;
• iron deficiency anemia;
• rheumatological diseases;
• depression, psycho-emotional disorders.

Patients with chronic diseases of the upper and lower respiratory tract, digestive system organs, rheumatism, thyrotoxicosis, vegetovascular dystonia face subfebrile condition. The cause of fever can be benign and malignant tumors, viral hepatitis, syphilis – diseases that do not show any specific signs at the initial stages.
If a person works with animals or has recently returned from a trip to exotic countries, a parasitic infection may be the cause of the fever. A similar danger awaits lovers of steak “with blood”, raw eggs and unpasteurized milk – products that can cause salmonellosis and other intestinal infections.

If subfebrile temperature is caused by an infectious effect, it is more difficult to tolerate, accompanied by a deterioration in well-being. Improvement occurs after taking antipyretic drugs.

Infections are not the only cause of fever. In thyrotoxicosis, the thyroid gland produces an excess amount of hormones. This can lead to a steady increase in temperature up to 37 °C. Iron deficiency anemia in some people is also accompanied by subfebrile condition. Another possible reason for a non-infectious increase in body temperature is a violation in the work of the very center of thermoregulation. In this case, an examination by a neurologist is required.

Diagnosis and treatment

A patient with a chronically elevated temperature should consult a physician. To determine the cause, a set of examinations is prescribed, which includes:

• general clinical blood and urine tests;
• biochemical blood test;
• coprogram;
• bacteriological cultures for genital infections, tuberculosis;
• fluorography;
• ECG;
• Ultrasound of the abdominal organs;
• gynecological examination and ultrasound of the pelvic organs.

Based on the results of the diagnosis, the patient is referred to specialized specialists: a cardiologist, gynecologist, endocrinologist, otolaryngologist, dentist.

To clarify the diagnosis, additional tests may be prescribed: for oncomarkers, for hormones, for rheumatoid factor. Once the cause is identified, the doctor prescribes and controls the treatment.

Thermoneurosis

Some people note an increase in temperature during psycho-emotional stress. This is how the body responds to stress. Experts call this manifestation a temperature neurosis.

To make a diagnosis, it is necessary to exclude other possible factors that lead to the appearance of subfebrile condition: infections, chronic diseases. The patient is given a so-called “aspirin test”. If the temperature drops after taking aspirin, then the cause is an infection. With thermoneurosis, temperature indicators after taking aspirin remain unchanged.

Subfebrile condition in this case is due to the reaction of the nervous system to physical and psychological overload. This phenomenon is most often encountered by adolescents and people of a neurotic warehouse, who are more difficult than others to react to stress. The transferred disease, trauma can give impetus to the development of thermoneurosis.
In the treatment of thermoneurosis, the priority is to change the patient’s lifestyle, the ability to relax, and cope with stress. A positive effect is given by reflexology, meditation, taking sedative herbal preparations, and moderate physical activity. In severe cases, it may be necessary to consult a psychologist, psychotherapist. The task of the specialist is to teach the patient to cope with stressful situations that provoke thermoneurosis.

Temperature increase after COVID-19

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March 17, 2021

Many patients who recover from COVID-19 often continue to increase body temperature to 37.2 – 37.5. Why is this happening? Let’s figure it out.

The thermoregulation center is located in the part of the brain called the hypothalamus.

The hypothalamus controls the processes of the endocrine system, which is closely interconnected with the most important organs for thermoregulation – the adrenal glands and the thyroid gland. So, with a decrease in ambient temperature, the release of thyroid hormones increases, accelerating the metabolism and, as a result, heat generation increases. When the weather changes, the adrenal glands secrete hormones into the blood that constrict or dilate blood vessels, including those of the skin. Because of this, the level of heat transfer changes.

Physiological fluctuations in body temperature during the day can be 1-1.3 degrees. Moreover, it always increases in the evening and can be normal from 4 to 6 pm in the armpit within 37.0 – 37.2. This is due to biorhythms and physiological processes in the body (lactation, menstruation in women, reaction to stress, pain, food intake, physical activity, special climatic conditions).

Coronavirus is known to have a damaging effect on the nervous system. Those. fluctuations in body temperature are explained by a direct lesion of the nervous system. Recovery takes a long time, sometimes several months.

Subfebrile temperature symptom is a manifestation of post-covid syndrome, which is not yet treated. This is a kind of asthenic syndrome that arose after an illness associated with an impressive inflammatory process. Recovery can take several months.

But the nervous system can be helped to recover faster:

► Sleep 7-9 hours every night.

► If possible, have a “quiet hour” during the day.

► Minimize the time spent in front of the screens of devices such as a smartphone, tablet, computer or TV.

► Get enough rest.

► Keep the room temperature at 22 degrees, constantly ventilate for fresh air.

► Observe the water regime – circular shower, contrast shower.

► Eat a balanced and healthy diet: lots of fresh fruits and vegetables, protein, no junk food, no fried foods, no alcohol, no caffeine. It is possible to use enteral nutrition with a high content of protein and energy, for example Nutridrink Compact Protein 125 g (1 plastic bottle) per day for 3-4 weeks.

► Walk outdoors and have regular light physical activity, (exercise therapy, yoga, especially breathing practices, meditation).

► Taking vitamin D at a prophylactic dosage of 2000 IU per day, Magne B6 forte 1 tab 3 r per day for 1 month.

► The use of acupuncture is also recognized by evidence-based medicine as a way to recover from past illnesses.

However, it is very important for people who have problems with the endocrine system to contact an endocrinologist and check the indicators. Additionally, you can determine the level of iron, ferritin, vitamin D in the blood. If there are deviations in the analyzes, start appropriate treatment. And in any case, when subfebrile temperature appears and persists for a long time, you should consult a doctor to identify possible problems.

What else is important besides measuring body temperature?

People in recovery, especially the elderly, should regularly monitor their pulse, blood pressure, be vigilant for heart complaints, monitor oxygen levels with a pulse oximeter.