What is fever?
Fever is an increase in your body’s temperature to a range that is above normal (98.6 degrees Fahrenheit). Normal body temperature can change throughout the day by a few degrees. Various factors can increase your body temperature including infection, eating, physical activity, medications, surrounding (room or outdoor) temperature, or a strong emotional response.
An oral temperature of 99.5 degrees Fahrenheit in a child and over 99 to 99.5 degrees Fahrenheit in adults is considered a fever. Fever can be caused by fairly benign conditions, such as a cold, or by serious conditions, such as influenza and meningitis. Infant teething, recent immunization, autoimmune and inflammatory disorders, and some cancers can cause a fever as well.
An extremely high fever can lead to seizures (called a febrile seizure) in children. These seizures do not usually cause permanent harm, but you should visit your health care professional if your child experiences a seizure. Seek emergency care if a seizure lasts more than a couple of minutes.
If your fever lasts more than 48 hours, is associated with other alarming signs, or causes you concern, seek prompt medical care. Fever in infants and very young children can quickly become serious, so exercise caution if your baby develops a fever. Seek immediate medical care (call 911) if you, or someone you are with, have a fever with excessive crying, difficulty breathing, stiff neck, or confusion. These are signs of a serious or life-threatening illness that should be immediately evaluated in an emergency setting.
What other symptoms might occur with fever?
Fever may be accompanied by other symptoms, depending on the underlying disease, disorder or condition. Fever is usually a sign of infection, which often leads to a variety of symptoms. This section describes relatively common as well as more serious symptoms that may accompany a fever.
Symptoms may occur along with fever
Fever may occur with other common symptoms including:
Aches and pains
Decreased urine output
General ill feeling
Hot, dry skin
Serious symptoms that might indicate a life-threatening condition
In some cases, fever may occur with other symptoms and certain combinations of symptoms that might indicate a serious or life-threatening condition that should be immediately evaluated in an emergency setting. Be particularly concerned about fever in infants two months of age or younger. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms:
Bluish coloration of the lips or fingernails
Change in level of consciousness or alertness, such as passing out or unresponsiveness
Extremely watery diarrhea, possibly with blood
High fever (higher than 101 degrees Fahrenheit)
Very bad headache
What causes fever?
Multiple types of infections, inflammatory disorders, and conditions can lead to a fever. More common infections include flu (influenza), pneumonia, appendicitis, and urinary tract infections. Rheumatoid arthritis and other connective tissue inflammatory conditions can also be present with a fever. Your baby may even have a fever when teething. Because there are so many possibilities, it is important to contact your doctor to address your concerns and answer your questions.
Possible causes of fever
Fever is a sign of many different types of infections:
Cellulitis (bacterial skin infection)
Common cold (viral respiratory infection)
Diverticulitis (inflammation of an abnormal pocket in the colon)
Gastroenteritis (“stomach flu”)
Urinary tract infection
Other causes of fever
Fever can also be caused by inflammatory conditions including:
Rheumatoid arthritis (chronic autoimmune disease characterized by joint inflammation)
Systemic lupus erythematosus (disorder in which the body attacks its own healthy cells and tissues)
Life-threatening causes of fever
In some cases, fever may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These conditions include:
Epiglottitis (life-threatening inflammation and swelling of the epiglottis, a tissue flap between the tongue and windpipe)
Influenza, particularly in the very old or young
Meningitis (infection or inflammation of the sac around the brain and spinal cord)
Tuberculosis (serious infection affecting the lungs and other organs)
Questions for diagnosing the cause of fever
To diagnose the underlying cause of fever, your doctor or licensed health care practitioner will ask you several questions related to your symptoms. Questions for diagnosing the cause of fever include:
When did the fever start?
How long have you had a fever?
Is the fever constant or intermittent?
Is the fever reduced by common over-the-counter medications, such as acetaminophen (Tylenol)?
What are the potential complications of fever?
A rise in temperature is your body’s natural way of killing the infectious agent or preventing its spread. A fever is a sign of an infectious or inflammatory process, many of which can be treated without serious difficulties. In most cases, the complications are due to the underlying problem, not the fever itself. However, there are potential complications of untreated or poorly controlled fever, some of which can be serious and even life threatening including:
Brain damage from an extremely high fever
Dehydration due a decreased desire to drink fluids
Dehydration due to vomiting or diarrhea
Long term physical disability