What is low-grade fever?
A fever is an increase in the body temperature above normal. A low-grade fever is a mild elevation of the temperature above normal. Your temperature measurements fluctuate through the day and vary depending upon the site of measurement. Generally, a child is considered to have a fever if the temperature is at or above 100.4 degrees Fahrenheit rectally, 99.5 degrees Fahrenheit orally, or 99 degrees Fahrenheit in the armpit. In an adult, a fever is generally defined as 100 degrees Fahrenheit (37.8 degrees Celsius) or greater
Fevers often accompany infections and are part of your body’s natural defense against them. Body temperature can also be elevated by physical activity and environmental factors, such as wearing heavy clothing or a high ambient temperature. A low-grade fever may also occur following immunizations, during teething, or as a symptom of cancer or inflammatory and autoimmune conditions. It can also occur as a side effect of some medications.
Low-grade fevers may not require treatment if other symptoms are absent. Self-care measures, such as rest and drinking fluids, may be enough. Medications, such as acetaminophen (Tylenol), ibuprofen (Advil, Motrin), and aspirin, can all lower a fever, although aspirin should not be used for children, and ibuprofen is not recommended for infants under six months of age.
Persistent fevers or high fevers may require medical intervention, as may those accompanied by such symptoms as sore throat, earache, cough, or burning with urination. Fevers can be serious in people who have weakened immune systems or who have chronic medical problems.
Low-grade fevers can occasionally accompany serious medical conditions. Seek immediate medical care (call 911) for serious symptoms, such as irritability or inconsolability in children, confusion, decreased levels of consciousness, difficulty breathing, difficulty walking, severe pain, neck rigidity, seizure, blue coloration of the lips or nails, or rapid heart rate.
If your low-grade fever is persistent or causes you concern, if you have other symptoms of infection, a weakened immune system, or have chronic medical problems, seek prompt medical care.
What other symptoms might occur with low-grade fever?
Low-grade fever may accompany other symptoms that vary depending on the underlying disease, disorder or condition. Conditions that frequently affect your temperature may also involve other systems.
Infection symptoms that may occur along with low-grade fever
Low-grade fever may accompany other symptoms of infection including:
Abdominal pain or cramping
Burning with urination, urinary frequency, or urgency
Muscle aches, joint aches, headaches, or earaches
Nausea with or without vomiting
Redness or tenderness of the skin
Shortness of breath
Other symptoms that may occur along with low-grade fever
Low-grade fever may accompany other symptoms including:
Ear pulling in children
Easy bleeding or bruising
Feeling hot without sweating
Joint deformity and reduced range of motion
Serious symptoms that might indicate a life-threatening condition
In some cases, low-grade fever may be a symptom of a life-threatening condition that should be immediately evaluated in an emergency setting. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:
Not producing any urine, or an infant who does not produce the usual amount of wet diapers
Rapid heart rate (tachycardia)
What causes low-grade fever?
Fevers often accompany infections. Body temperature can be elevated by physical activity and environmental factors, such as wearing heavy clothing or a high ambient temperature. A low-grade fever may also occur following immunizations, during teething, or as a symptom of cancer or inflammatory and autoimmune conditions. It can also occur as side effect of some medications.
Infectious causes of low-grade fever
Low-grade fever may be caused by infections including:
Cellulitis (skin infection)
Childhood diseases, such as chickenpox, fifth disease, measles (contagious viral infection also known as rubeola), mumps (viral infection that, in part, affects the salivary glands in the neck), whooping cough (pertussis)
Cold, flu, or other viral infections
Gastroenteritis (infection of the digestive tract)
Mononucleosis (viral infection)
Other causes of low-grade fever
Low-grade fever can also be caused by conditions including:
Medication side effects
Rheumatoid arthritis (chronic autoimmune disease characterized by joint inflammation)
Vasculitis (inflammation of blood vessels)
Serious or life-threatening causes of low-grade fever
In some cases, low-grade fever may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:
Acute hepatitis (active infection of the liver)
Diverticulitis (inflammation of an abnormal pocket in the colon)
Encephalitis (inflammation of the brain)
Epiglottitis (life-threatening inflammation and swelling of the epiglottis, a tissue flap between the tongue and windpipe)
Meningitis (infection or inflammation of the sac around the brain and spinal cord)
Osteomyelitis (bone infection)
Pancreatitis (inflammation of the pancreas)
Questions for diagnosing the cause of low-grade fever
To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your low-grade fever including:
How long have you had a low-grade fever?
Does it come and go, or is it constant?
Does anything make it go away?
Do you have any chronic medical problems or a weakened immune system?
Have you traveled recently?
Do you have any other symptoms?
What medications are you taking?
Because low-grade fever can be due to serious diseases, failure to seek treatment if it is persistent or accompanied by concerning symptoms, or if you have chronic medical conditions or a weakened immune system, can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including: