The causes of low-grade fever include infections and conditions such as leukemia, Crohn's disease, pulmonary embolism, rheumatoid arthritis and vasculitis, according to Healthgrades. The condition can also occur as a side effect of medications, and as a result of life threatening conditions such as appendicitis, pancreatitis, heat exhaustion and meningitis.
Examples of infections that result in a low-grade fever include cellulitis; bacterial infection such as scarlet fever; ear infection; human immuno-deficiency virus, or HIV; and lung infections including tuberculosis and pneumonia, notes Healthgrades. Other causes of a low-grade fever are infections such as gastroenteritis, which is a digestive tract infection; childhood conditions, which include measles, chickenpox, whooping cough and mumps; and urinary tract infection.
Low-grade fever may lead to serious complications and irreversible damage if the condition is not treated in time, states Healthgrades. Such complications may include anemia, cancer spread, heat stroke, liver scarring and brain damage. As a result, sufferers of low-grade fever should seek immediate medical care if the condition persists.
In the diagnosis of the cause of low-grade fever, a doctor may seek to know the duration of the condition, whether the condition is constant or sporadic, the medications that a patient is taking, and whether the patient experiences other symptoms, states Healthgrades. He may also seek to know if the patient suffers from a chronic disease or weak immune system, and if there is anything that makes the fever disappear.