Fever, or pyrexia occurs when the internal body temperature goes up to a level that is considered above normal. It indicates another underlying condition usually infection.
Average body temperature is about 98.6 °Fahrenheit (37 °Celsius), and temperatures above 100.4 °F (38 °C) are indeed considered to be a fever. Three of the common sites for checking temperature are the mouth, under one’s arm, as well as the rectum.
Although it causes much discomfort, fever is not dangerous on its own. However, among young children, older adults, or individuals with other health concerns, fever needs to be checked out by a doctor.
Facts on fever
- Common symptoms of a fever are chills and shaking
- Bacterial or viral infections are also common causes.
- A fever can be also part of the body’s way to fight infection.
- Aspirin as well as acetaminophen can also help reduce fever, but aspirin is not suitable for children.
A fever is not considered usually a problem in itself, but a symptom of another health condition. It does indicate that there is something wrong with some part of the body.
It can occur when something goes wrong with one of a wide range of functions.
A fever can also help the body fight infection, because it increases the amount of antiviral as well as anticancer interferon in the blood. This makes it rather difficult for bacteria and viruses to replicate.
Body temperature can also help measure the success of medical treatments.
Conditions that cause a fever
Infections happen to be the most common cause of fever, but various conditions, illnesses, and medicines can also raise the body temperature.
- infections cum infectious diseases, such as influenza, common cold, HIV, malaria, infectious mononucleosis, and gastroenteritis
- legal and illegal drugs, including antibiotics, amphetamines as well as cocaine
- trauma or injury, such as a heart attack, stroke, heatstroke, heat exhaustion, or burns
- damage to one’s tissue, such as from hemolysis (breaking open of red blood cells in order to release hemoglobin), surgery, heart attack, crush syndrome as well as hemorrhage
- other medical conditions, such as skin inflammation, arthritis, hyperthyroidism, some cancers, lupus, inflammatory bowel disease, blood clots, metabolic disorder, gout, and embolisms
- Antibiotics, narcotics, barbiturates, and antihistamines can also cause “drug fevers” due to adverse reactions, withdrawal, or due to the design of the drug.
- acute, which lasts less than 7 days, as in the case of a viral upper respiratory tract infection
- sub-acute, lasting up to 14 days such as typhoid
- chronic or persistent, lasting over 14 days, as in tuberculosis, HIV, and cancers
These can also be classed based upon severity:
- low grade
Fevers can be:
- sustained or continuous, whereby they it does not fluctuate more than 1.5 °F (1 °C) over 24 hours, but is never normal in this time
- intermittent, when the fever does occur for several hours in the day, but not all the time
- remittent, when it does fluctuate by more than 2 °C but does not become normal
- Typhoid can underlie a sustained fever, tuberculosis also causes an intermittent fever, and infective endocarditismay also trigger a remittent fever.
- Fevers that exist for days or weeks with no explanation are referred to as fevers of undetermined origin (FUO).
A fever is a symptom, but it can also occur with its own symptoms and with other symptoms.
A person who has a fever may also have:
- a high temperature
- shivering, chills, and shaking
- intermittent or excessive sweating
- skin flushing
- feeling weak, dizzy, or faint
Body temperature measurements do vary and therefore doctors do see signs of sickness that can also accompany fever.
- low appetite
- increased pain sensitivity
- increased pain sensitivity
- inability to concentrate
Young children with a fever need to see a doctor, but older children and adults do not always need to do so. They need rest and must remain hydrated. Adults may take acetaminophen, ibuprofen, or aspirin to reduce the temperature. Children must not take aspirin.
A person with a fever is at risk of dehydration, so they should drink plenty of fluid.
It may help to:
- wear less clothes
- cool the room, for example, using a fan
- put a cool damp cloth on the forehead
- take a cool bath
If a child aged 0 to 36 months has a fever, a doctor must be consulted.
Symptoms may include:
- a stiff neck
- severe headache
- altered mental status
- joint swelling
- burning with urination
- chest pain
- productive cough
- abdominal pain
- a fever that is consistently high for more than 3 days
In cases where fever escalates so high that tissue damage is likely, the fever must be brought under control.
How is body temperature measured?
Body temperature is indeed measured by placing a thermometer in one’s mouth, ear, anus, or even arm. The readings may not necessarily be the same.
Body temperature also vary after eating, during periods of high activity levels, wearing different clothing, or after smoking, being in warmer or colder rooms, and at various times of a woman’s menstrual cycle.
It can also depend on the time of day. It is often lower in the morning than during the day or in the evening.
With the above variations in mind, the table below also summarizes the average daytime temperatures for each measurement location as well as the temperature usually considered febrile or feverish for an adult.
If a child under 4 months of age has a rectal temperature of over 100.4° F or 38° C, they should see a doctor immediately.
Other warning signs in young children that do require immediate attention:
- look very ill
- being drowsy or even fussy
- already having a weakened immune system
- having a seizure
- having a sore throat, rash, stiff neck, earache, or headache
If a child aged 0 to 36 months is suffering from fever, he or she should see a doctor in case the cause has not been clarified and if there are other symptoms such as lethargy or a rash.
Aspirin is not suitable for children as there is risk of Reye’s syndrome.
A fever is easy to measure, but it can be indeed difficult to determine its cause. A doctor will check out with other symptoms, medications, recent travels, as well as other infection risks in order to diagnose what the cause might be. Any underlying cause that does need treatment can then be dealt with.