Fever facts
What is a fever?
What causes a fever?
What are the signs and symptoms of a fever?
How do health care professionals diagnose a fever?
How should someone take a temperature for fever?
What is the treatment for a fever?
What are home remedies for a fever?
When should someone seek medical care for a fever?
What kind of doctors treat a fever?
What are complications of a fever?
What is the prognosis for a fever?
Is it possible to prevent a fever?
Where can people find more information about fevers?
Fever is not considered medically significant until body temperature is above 100.4 F (38 C), which is the temperature considered to be a fever by medical professionals. 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 infection-fighting defenses against bacteria and viruses that cannot live at a higher temperatures. For that reason, low-grade fevers should normally go untreated, unless accompanied by troubling symptoms or signs.
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, sinus congestion, fatigue, joint pains or aches, chills, nausea, etc.
Fevers of 104 F (40 C) or higher may be dangerous and demand immediate home treatment and prompt medical attention, as they can result in delirium and convulsions, particularly in infants, children, and the elderly.
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. Heat exhaustion and heat stroke are forms of hyperthermia. Other causes of hyperthermia can include side effects of certain medications or medical conditions.
Fever should also not be confused with hot flashes or night sweats due to hormonal changes during perimenopause (the time period around menopause). Hot flashes and night sweats cause a sudden and intense feeling of heat, and may be accompanied by flushing (skin redness and tingly feeling) and sweating, but are not the same thing as a fever.
Place the tip of the digital thermometer in a child's armpit.
Leave the thermometer in place about one minute or until one hears a beep to check a digital reading.
Measuring fever by eardrum temperature
Tympanic (ear) thermometers must be placed correctly in a child's ear to be accurate. Too much earwax can cause the reading to be incorrect.
Eardrum temperature measurements are not accurate in small children and should not be used in children under 3 years (36 months) of age. This is especially true in infants below 3 months of age when obtaining an accurate temperature is very important.
Measuring fever by oral temperature
People 4 years old and older can have their temperature taken with a digital thermometer under the tongue with their mouth closed.
Clean the thermometer with soapy water or rubbing alcohol and rinse.
Turn the thermometer on and place the tip of the thermometer as far back under the tongue as possible.
The mouth should remain closed, as an open mouth can cause readings to be inaccurate.
The thermometer should remain in place for about one minute or until one hears the beep. Check the digital reading.
Avoid hot or cold drinks within 15 minutes of oral temperature measurement to ensure correct readings.
Measuring fever by rectal temperature
The American Academy of Pediatrics recommends rectal temperature measurements for children and toddlers under 3 years of age, as this gives the most accurate reading of core temperature.
Clean the thermometer with soapy water or rubbing alcohol and rinse with cool water.
Use a small amount of lubricant, such as petroleum jelly, on the end.
Place the child or baby prone (belly-side down) on a firm surface, or place a child face up and bend his legs to his chest.
After separating the buttocks, insert the thermometer approximately ½ to 1 inch into the rectum. Do not insert it too far.
Hold the thermometer in place, loosely keeping one's hand cupped around the child's bottom, and keep one's fingers on the thermometer to avoid it accidently sliding further into the rectum. Keep it there for about one minute, until one hears the beep.
Remove the thermometer, and check the digital reading.
Label the rectal thermometer so it's not accidentally used in the mouth.
A rectal temperature will read approximately 1 degree higher than a simultaneously obtained oral temperature.
Other home remedies for fever include staying hydrated. Drink plenty of water and fluids, and avoid alcohol or caffeinated beverages, which can contribute to dehydration. Popsicles can also be cooling and provide fluids while also soothing a sore throat if that is present.
A fan to circulate air or an open window may be helpful, as well as applying a cool damp washcloth to the forehead. If you are caring for a child, make sure the child does not feel too cold.
A fever over 104 F/40 C in children and adults is considered dangerous. Seek medical attention immediately.
Any child below 3 months of age who has a temperature of 100.4 F (38 C) or greater should be seen by a physician. If a child or adult has a history or diagnosis of cancer, AIDS, or other serious illness, such as heart disease, diabetes, or is taking immunosuppressant drugs, medical care should be sought for a fever.
Children with a fever who have signs and symptoms such as rash, sore throat, ear pain, stiff neck, drowsiness, fussiness, or headache should see a doctor. In addition, if a fever lasts more than one day in a child or toddler 2 years of age or under, or last more than three days in a child over age 2, seek medical care.
Otherwise, observe the person with the fever. If he or she appears sick or has symptoms that would suggest a major illness, such as meningitis (headache, stiff neck, confusion, problems staying awake), urinary tract infection (shaking chills, back pain, burning with urination), pneumonia (shortness of breath, cough), or any other signs of a serious illness, contact a health care professional.
Other symptoms that may be indicative of a severe illness include repeated vomiting, severe diarrhea, or skin rashes (that could be a sign of dengue fever, Rocky Mountain spotted fever, scarlet fever, rheumatic fever, strep throat, or chickenpox).
Fever blisters (herpangina) are small blisters that turn into ulcers, usually on the lips, mouth, or tongue; a virus causes fever blisters. When a child contracts this virus for the first time, the symptoms and the fever blisters can be quite severe. If the child is not eating or drinking, contact the child's pediatrician.
Women who are pregnant should contact a doctor for a fever over 101 F (38 C). A fever during pregnancy that is accompanied by a rash and joint pain could be a sign of an infection that could affect the baby. Some infections, such as cytomegalovirus (CMV), can cause congenital deafness and other problems in the baby. If a pregnant woman contracts the Zika virus (also called Zika fever), it may cause a birth defect called microcephaly (small head).
On the other hand, if the fever accompanies a simple cold or virus, one can treat the fever as described above and be assured the fever is only a symptom of the illness. This is not to say one should ignore a fever. If there are other associated symptoms that are bothersome, contact a doctor.
Some vaccines given in childhood can cause a low-grade fever within a day or two of getting the injection. This fever is usually self-limited and short-lived. If the reaction seems severe or the skin at the injection site is red, hot, and painful, contact the child's doctor.
A low percentage of all children and toddlers between 18 months to 3 years of age will have a seizure (convulsion) with a high fever. Of those with a history of febrile seizure, some will have another seizure associated with another febrile (fever) episode. Febrile seizures, while frightening to the parents, are not associated with long-term nervous-system complications. Children used to be prescribed the antiseizure drug phenobarbital (Solfoton, Luminal) following a febrile seizure as a preventive measure (prophylaxis). This has not been shown to be beneficial and possibly may be harmful, so it is not recommended.
Recurrent fever in children (three or more episodes of fever in a six-month period, with no apparent causative illness) can be a symptom of a few different illnesses, such as PFAPA (periodic fever, aphthous ulcers, pharyngitis, and adenopathy) syndrome, cyclic neutropenia, Epstein-Barr virus (EBV) infection, and others. See your child's pediatrician if fevers are recurrent.
Recurrent, persistent, or chronic fever in adults may accompany immune-deficient fever of unknown origin (FUO), also known as neutropenic FUO, and HIV-associated FUO, as well as many other infectious conditions. Adults should see their doctors if they develop recurrent fever.
Any kind of doctor is able to treat a fever, but most likely when you have a fever you will see your family medicine specialist (also called a general practitioner) or internist, and your child will see a pediatrician. You may see an emergency medicine specialist in an emergency department.
If fever is due to a specific underlying or recurrent medical condition, you may see a specialist for that particular condition. For example, if a person has cancer and a fever, an oncologist may be consulted. A pregnant woman with a fever may see her obstetrician. Newborns with fever may see neonatal specialists. Patients with HIV/AIDS and fever may consult an infectious disease specialist.
While having a fever is generally very uncomfortable, a fever itself does not usually cause severe complications.
High fever (>103 F/40 C) or prolonged bouts of fever can lead to
seizures,
hallucinations, and/or
It is important to seek treatment for the underlying cause of a fever in the situations described above. Many of the infections that can cause fever can lead to severe complications if untreated.
The prognosis for a fever and how long it lasts depends on the cause. Most cases of fever are self-limited and resolve with symptomatic treatment. For example, a fever associated with a common cold usually only lasts two to three days. If fever is caused by influenza, most flu symptoms including fever go away in about a week. Depending on the cause, antibiotics or other appropriate medications may be used.
Fevers associated with severe infections, or in patients whose immune system is compromised (such as those with cancer, elderly people, newborn infants, patients with HIV/AIDS, or people with autoimmune disorders), can be life-threatening.
Prevention of fever is possible only to the extent that the specific cause of the fever can be prevented. Most fevers are caused by infection. Avoiding sources of infection and maintaining good hygiene practices are the best way to prevent a fever.
Some ways to prevent the spread of infection include the following:
Proper hygiene: Wash hands frequently.
Avoid contact with sick people.
Make sure immunizations are up to date.
Every year in the United States, on average, 5%-20% of the population gets the flu, more than 200,000 people are hospitalized from flu complications, and about 36,000 people die from flu. The flu is highly infectious and is a serious viral respiratory infection. Flu vaccine is an inactivated vaccine, meaning that it contains killed influenza virus. Anyone who wishes to reduce their risk of getting the flu can be vaccinated, however the U.S. Centers for Disease Control and Prevention recommends that people who are at risk for serious complications from the flu be vaccinated each year.
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