Alternative Names pyrexia, elevated body temperature
Definition Fever is a higher-than-normal body temperature. Normal temperature is usually defined as 98.6 degrees Fahrenheit (F) or 37 degrees Celsius (C). Many doctors would say a person truly has a fever when their temperature is greater than 99.5 degrees F or 37.5 degrees C.
What is going on in the body? Normal body temperature changes during the day. Exercise, stress , or dehydration may cause a person's temperature to go up. In these cases, it is not considered a true fever. Fever is a symptom, not a disease. A fever may mean that there is something else going on in the body that is causing it. Fever helps the body fight infections by making the body's defence systems work more efficiently. Bacteria and viruses cannot live at higher temperatures and so are killed by fever.
What are the signs and symptoms of the condition? The signs and symptoms of a fever depends on what is causing it. At first, a fever can cause a chill. When the brain raises the body's "thermostat," the body responds by shivering to raise the temperature. Shivering produces heat in the body. Once the temperature goes up, the person often feels warm. When the fever goes away, the person may start to sweat. [Fauci]
What are the causes and risks of the condition? Fever can be caused by many conditions, including: infections such as strep throat caused by group A strep , pneumonia , flu and chickenpox tissue injuriestumours or cancer diseases that cause inflammation, such as rheumatoid arthritis medicationsbeing in a hot environment for too long The main risk of mild or moderate fevers is dehydration . People need more fluids than usual when they have a fever. A fever greater than 106 degrees Fahrenheit or 41 degrees Celsius can result in brain damage and death in some cases. This level of fever is very unusual. It is not usually brought on by common illnesses. Fever in children presents special concerns for parents, since some children have febrile seizures with fever. These can lead to injury to the child, but this is rare.
What can be done to prevent the condition? Generally, nothing can be done to prevent fever. A person can get a fever by being in a hot environment for too long and not drinking enough fluids. It is important to avoid being in the heat for too long, and follow sports safety principles in summer . It is also important to drink more fluids than usual when it is very hot outside.
How is the condition diagnosed? A thermometer is used to measure the temperature. The temperature can be taken in the mouth, rectum, ear, or under the arm. Other tests may be used to diagnose the cause of the fever, including blood, urine and x-ray examinations.
What are the long-term effects of the condition? Mild or moderate fever generally has no long-term effects. The dehydration caused by fever can be avoided by drinking extra fluids. Fevers greater than 106 degrees F or 41 degrees Celsius can sometimes result in brain damage or death if the fever is not treated within several hours.
What are the risks to others? A person with a fever may have an infection that is contagious. If other conditions are causing the fever, there are no risks to others.
What are the treatments for the condition? Treatment is usually directed at whatever is causing the fever. Some steps that can help bring down a fever or comfort a person include the following: Paracetamol or ibuprofen can help reduce a fever. A fever may return after the first dose of medication. These medications should be taken as directed throughout the day. Extra fluids should be taken to help avoid dehydration . Sponging or bathing in lukewarm water can cool the skin and reduce body temperature. Ice water or alcohol sponge baths are no more effective than lukewarm water, so these should not be used. Extra clothing and blankets are not necessary. Bundling a person will only cause the fever to rise. Fevers greater than 40 to 41 degrees Celsius are very serious. These high fevers need to be treated in the hospital.
What are the side effects of the treatments? Aspirin should not be given to children or adolescents. A rare condition called Reye's syndrome , a severe inflammation of the brain and liver, has been linked to aspirin use in young people, especially in cases of the flu and chickenpox . All medications have side effects, including allergic reactions and stomach upset. Other side effects depend on the medication used.
What happens after treatment for the condition? What happens after treatment depends on what caused the fever. If the cause of the fever is corrected, the fever generally goes away. Further treatment may not be required.
How is the condition monitored? The temperature can be taken several times to monitor the fever. Further monitoring depends on the underlying cause of the fever.
Author: Adam Brochert, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 12/06/2005 Contributors Potential conflict of interest information for reviewers available on request
