The normal human body temperature is about 98.6°F, but it fluctuates throughout the day. A fever is when the temperature rises above a normal range.
A low grade fever occurs when the body temperature becomes very slightly elevated, 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.
Some people may hardly notice that they have a low grade fever. However, others may experience various symptoms, including:
- feeling warm to the touch
- muscle aches
- 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 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:
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.
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:
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.
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.
The person may also experience other symptoms of cancer, including:
- persistent fatigue
- 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.
Many other chronic disorders may cause symptoms such as a low grade fever, including:
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.
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.