What is Low Grade Fever?
A low grade fever is when your body temperature is slightly above the normal level of 37 degrees.
There are a multitude of possible causes relating to this symptom. They can range from mild issues all the way up to severe and possibly life-threatening conditions.
How long a low grade fever lasts for depends on what is provoking it and potential treatment. (1)
The temperature of your body is regulated by the hypothalamus. This area of the brain works to keep you at a healthy 37 degrees celsius.
However, the ideal body temperature of every person may differ slightly. Some people may have a marginally lower or higher average temperature than this figure.
Fevers are caused when your brain sets your temperature to a higher rate. Anything above 38 degrees celsius is considered a fever. (2)
A high grade fever is a temperature above 39.5 degrees celsius. Very high fevers are higher than 41 degrees celsius. (3)
A low grade fever registers an elevated body temperature lower than around 38 degrees celsius but above 37.4 degrees. As with high fevers, low grade fevers can occur for multiple reasons. (4)
Conditions and factors that can cause a low grade fever include the following:
Certain medication can cause an elevated body temperature. They may cause an immune response or increase your metabolic rate, resulting in fever.
A fever caused by any kind of medication is referred to as drug fever. It is usually due to sensitivity and appears within 7-10 days after starting treatment. (5)
Drug fever is usually a stand-alone symptom. In some cases, it can include increased heart rate and faster breathing. (6)
Psychogenic fever is an illness related to stress. When put under pressure, patients can experience a long-lasting low grade fever..
In other cases the low grade fever could point towards one particular factor. For example, a nurse was interviewed about the most stressful parts of her job.
Before the interview began, her temperature was a regular 37.2 degrees celsius. By the end of it, her temperature had increased to 38.2 degrees celsius. (7)
If an extremely emotional or stressful event happens, the fever may increase even higher. Patients can develop a temperature up to 41 degrees.
This disease typically affects young women. In some cases, the low grade fever can persist for a period of months or years.
Traditional drugs used to treat fever are not effective against the psychogenic type. Instead, the fever can be reduced with anti-anxiety drugs or therapy. (8)
Endometriosis is a disease affecting women. It causes uterus tissue to grow outside the uterus. This unusual tissue growth is usually very painful.
During the menstrual cycle, tissue from the uterus is broken down. With endometriosis, the same thing happens but in other parts of the body, for example: the pelvis. (9)
If left untreated, this disease can cause infertility. Symptoms include: low grade fever, pelvic pain, fatigue and abnormal menstruation. (10)
Thyroiditis is caused when hormones leak from the thyroid gland. Postpartum thyroiditis and so-called “silent” thyroiditis and is usually painless.
Contrastingly, subacute thyroiditis can be agonising. It results in the thyroid becoming enlarged and inflamed. This condition can last for several months. (11)
The thyroid gland is located in your neck, which means pain can begin to spread to your jaw and ears. A characteristic early sign of this condition is low grade fever.
Other common symptoms are fatigue and pain in the muscles and joints. When the thyroid becomes more inflamed, the surrounding areas become more sensitive. (12)
A pulmonary embolism is when an artery in your lungs becomes blocked. The blockage is usually a blood clot originating from another area of the body.
As the clot can hamper blood from flowing into the lungs, it can be fatal if not treated. The faster you receive treatment, the better the outcome for your health.
Difficulty breathing, pain in the chest and swelling in the legs are typical symptoms. However, a pulmonary embolism can also occur without clear symptoms. (13)
A low grade fever can be a warning of an upcoming pulmonary embolism. A review of pulmonary embolism patients revealed some patients had a low grade fever for over a week before diagnosis. (14)
Hodgkin’s lymphoma is a type of cancer that affects your lymph tissue. This cancer can start off in any area with lymphoid tissue.
This means your digestive tract, bone marrow, and lymph nodes can be affected. The cancerous cells can then spread through your lymph vessels.
Hodgkin’s lymphoma commonly originates in the upper body’s lymph nodes. Typical areas include the neck, chest and underarm area. (15)
A low grade fever lasting for more than several days can be a symptom. Other potential signs include night sweats preceded by a slight temperature rise. (16)
The primary symptom of a low grade fever is a temperature that a little higher than the benchmark 37 degrees. It’s precisely defined as a temperature between 37.5 and 38.3 degrees celsius. (17)
You may also experience other symptoms such as:
Headaches are a common symptom of fevers. A survey revealed 63 percent of the general population reported fever as the cause of headaches. (18)
Generally, the higher your fever the greater the risk of a headache. (19)
The increase in your body’s core temperature can lead to sweating. You might also have flushed warm skin. (20)
Chills and Shivering
You can feel chilled and even shiver if you are getting a fever. This is a result of your body adapting to the increase in body temperature. (21)
Discovering the root cause of a fever can be a difficult task.
A large study on patients with fevers explored ideal diagnosis strategies. The subjects included patients with fevers of unknown origin (FUO) and low grade fevers.
As with any type of fever, a low grade fever can occur for various reasons. The underlying causes can be minor or serious.
Researchers concluded that diagnosing low grade fevers requires the same thorough approach as FUO. (22)
To diagnose why you’re experiencing a low grade fever, your doctor might take the following approaches:
Your doctor will review any medication you are taking. If you are sensitive to a drug, it can cause drug fever.
This response will usually occur between 7 and 10 days after you begin treatment. Some medications, like penicillin, are known to cause fever in some patients.
Your doctor may suggest taking you off the drug in question to see if your fever disappears. (23)
Your doctor will catalog any other symptoms you present with low grade fever. A full history of your health will be provided to your doctor.
Usually, these two factors will provide clues as to what’s wrong. Depending on the suspected cause, you may receive other tests such as a blood analysis. (24)
If no diagnosis is reached, the doctor will likely review your case thoroughly. The results of any tests will be reviewed again, and advice may be requested from medical colleagues. (25)
What is low grade rever? A low grade fever is a temperature between 0.5 to 1.3 degrees celsius higher than normal body temperature of 37 degrees celsius.
How do doctors test for low grade fever? Doctors will check whether any prescribed medication could be causing the fever. If not, a physical exam will be performed to evaluate any other symptoms. Further testing may be performed to match all symptoms with a cause.
When should you go to the doctors with low grade fever? If your fever is persistent, it is always best to seek medical attention. Accompanying symptoms such as shortness of breath, chest pain or dramatic weight loss require urgent medical attention.
Can you prevent low grade fever? Good health practices can reduce your risk of certain conditions which result in low grade fevers. However, it is impossible to prevent all potential diseases and illnesses causing such fevers.
What can relieve low grade fever? Depending on the cause, a low grade fever may be relieved by antipyretic drugs. These is a type of medication formulated to reduce fever. (26)
What are the causes of low grade fever? Causes of low grade fever include stress response or sensitivity to a drug. They can also manifest due to serious issues such as hodgkin’s lymphoma and pulmonary embolism.
Is low grade fever life threatening? Low grade fevers are not a life threatening condition. However, they can be an indication of a grave health issue.
Low grade fevers are a symptom that is generally non-specific. This means it can be difficult to find out why you’re experiencing this elevated temperature.
It is important to note body temperature can fluctuate. When exercising, your temperature goes up. The same can happen when it is very hot outside. (27)
Some symptoms along with low grade fever can indicate a serious problem. Low grade fever on its own is not a dangerous condition, but it can indicate an underlying issue.
Also, not everyone has a precise body temperature of 37 degrees celsius. Which means you may experience 0.5 degrees of higher or lower variation. (28)