John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Although a fever could be considered any body temperature above the normal 98.6 F (37 C),
medically, a person is not considered to have a significant fever until the temperature is above 100.4 F (38.0 C).
Most fever is beneficial, causes no problems, and helps the body fight off infections. The main reason for treating a fever is to increase comfort.
Fever is the result of an immune response by your body to a foreign invader. These foreign invaders include viruses, bacteria, fungi, drugs or other toxins.
Children under 3 months of age with a temperature of 100.4 F (38.0 C) or greater should be seen by a health care
professional. They may be quite ill and not show any signs or symptoms besides a fever. Infants less than 6 weeks
of age should be seen immediately by their doctor.
Acetaminophen (Tylenol and others) and ibuprofen (Advil, Motrin) can be used to treat a fever. Aspirin should not be used in children or adolescents to control fever.
The prognosis for a fever depends on the cause. Most cases of fever are self-limited and resolve with symptomatic treatment.
A person who is taking immunosuppressant drugs or who has a history of or
diagnosis of cancer, AIDS, or other serious illness, such as heart disease or diabetes, should
seek medical care if a fever develops.
What is a fever?
Fever refers to an elevation in body temperature. Technically, any body temperature above the normal oral measurement of 98.6 F (37 C) or the normal rectal temperature of 99 F (37.2 C) is considered to be elevated. However, these are averages, and
one's normal body temperature may actually be 1 F (0.6 C) or more above or below the average of 98.6 F. Body temperature can also vary up to 1 F (0.6 C) throughout the day.
Fever is not considered medically significant until body temperature is above 100.4 F (38 C). Anything above normal but below 100.4 F (38 C) is considered a low-grade fever. Fever serves as one of the body's natural defenses against bacteria and viruses which cannot live at a higher temperature. For that reason, low fevers should normally go untreated, unless accompanied by troubling symptoms.
Also, the body's defense mechanisms seem to work more efficiently at a higher temperature. Fever is just one part of an illness, many times no more important than the presence of other symptoms such as cough, sore throat, fatigue, joint pains or aches, chills, nausea, etc.
Fevers of 104 F (40 C) or higher demand immediate home treatment and subsequent medical attention, as they can result in delirium and convulsions, particularly in infants and children.
Fever should not be confused with hyperthermia, which is a defect in your body's response to heat (thermoregulation), which can also raise the body temperature. This is usually caused by external sources such as being in a hot environment.
Reviewed by Melissa Conrad Stöppler, MD on 5/4/2012
When to Call the Doctor: Fever, Nausea, Diarrhea, Colds, and Coughs
Fever is a routine symptom in infants and children. It is a normal immune response to an infection to generate an elevated body temperature and make the body inhospitable. That doesn't mean that the fever should be ignored, but if the child is otherwise doing well, treating the fever with over-the-counter (OTC) medicines such as acetaminophen or ibuprofen may be all that is needed.
Fever in an adult is a different situation, because the patient is old enough to identify associated complaints and symptoms, and can provide a past medical history. Fever is a systemic response to inflammation. Patients with compromised immune systems and a fever are a completely different scenario. Those with immune system conditions or disease do not function as well as those who are not immunocompromised, and their body may not be able to fight off infection adequately. For example
people receiving chemotherapy for cancer,
those who take drugs to treat chronic inflammation such as rheumatoid arthritis or systemic lupus erythematosus,
individuals with HIV/AIDS may be so immunocompromised that their body may not be able to respond appropriately to an infection, and
older people may be very ill, but do not have a high fever (lower than 100 F [37 C]).