If an adult’s body temperature rises above the typical range of 98 to 100°F (36 to 38°C), they may have a fever. This is a common sign of an infection.
When an infection occurs, the immune system will launch an attack to try to remove the cause. A high body temperature is sometimes part of this reaction.
As a person’s body temperature increases, they may feel cold until it levels off and stops rising. People describe this as “chills.”
Read on to learn more about the symptoms of a fever, as well as some causes and treatment options.
A fever is a higher-than-typical body temperature that occurs as part of the immune response. A person
a fever if:
their chest or back feels hotter than usual
their skin is
to the touch
they feel hot and sweaty,
, or both
they have
skin
Depending on the cause, people may also have other symptoms such as:
fatigue
a general feeling of being unwell (
)
a
a
or
nose
Fever is distinct from temporary rises in body temperature due to other factors, such as exercise or hot weather.
People can test for fever at home by using a digital thermometer. To
:
Clean the tip using cold water and soap, and then rinse it.
Turn on the device.
Place the tip under the tongue, toward the back of the mouth, and close the mouth.
Wait until there is a flash or the thermometer beeps.
Read the temperature.
If the reading is 100.4°F (38°C) or above, the person may have a fever.
People can also use digital thermometers under the armpit. However, be aware that a typical armpit temperature will be around 0.5 to 0.9ºF (0.3 to 0.5°C) lower than oral temperature.
Ear thermometers are also available, but they can require precise positioning for an accurate result.
Digital thermometers are one of the safest methods for measuring body temperature at home. Glass thermometers can be dangerous if they break, and forehead strips are not accurate. People should not use these methods.
In many cases, the cause of a fever is a
, such as the flu or
. Most people get better from these infections with rest, fluids, and fever-reducing medications.
However, it is important to take steps to prevent the spread of the infection to protect people who are vulnerable to complications,
older adults and pregnant people. If COVID-19 is a possibility, stay home and seek advice about testing.
Sometimes, a fever indicates another type of condition that may require medical treatment. Contact a doctor as soon as possible if a person has a fever along with:
pain anywhere in the body, such as the face, ears, or throat
swelling anywhere in the body
a wound that is inflamed or leaking pus
signs of
sexually transmitted infection
, such as unusual
or
vomiting or diarrhea
symptoms that get progressively worse
symptoms that get better but then come back again
Any adult with a temperature over
should get emergency medical attention. This is known as
, which can have serious consequences if left untreated.
People should also seek immediate medical treatment if a person has a fever of any temperature along with:
chest pain
rapid breathing
difficulty breathing
coughing up pus or blood
a
, gray, or white tint to the lips or fingers
a severe headache
an aversion to light
confusion
drowsiness
signs of severe
, such as a lack of sweat, saliva, or urine
seizures or convulsions
Additional signs that a child needs immediate medical attention include:
a fever of any temperature in a child
a fever of 104°F (40°C) or more that does not reduce with medications
a fever that has lasted
sunken eyes, a soft spot on top of a baby’s head, or no tears when crying
A fever occurs when body temperature increases above its usual “set point”. Often, this is because the immune system is fighting a viral, bacterial, or other type of infection.
that affect or activate the immune system can also cause fever, such as:
autoimmune conditions, such as
or
inflammatory conditions, such as
neurogenic fever, which is when a neurological condition, such as
, elevates body temperature
certain cancers
some medications
Increases in body temperature from other causes include:
sunburn
some medications
A fever is a symptom, not an illness. A doctor can diagnose a fever by checking the person’s body temperature, but they will also need to diagnose the reason for the fever.
To do so, they will examine the individual and ask about any other symptoms and their medical history. To confirm a diagnosis, the doctor may recommend:
a blood test
a urine test
imaging tests
A fever does not always require treatment. Whether it does depends on its severity and the underlying cause. A doctor may recommend:
Fluids: If a person is
a lot, they may experience dehydration. In this case, they should consume
to prevent complications.
Fever-lowering medications: Antipyretics help to lower a person’s temperature. Doctors may recommend these for
, but they are not always necessary. Examples include
(Tylenol),
, and
. Do not give aspirin to children. Always consult a doctor or pharmacist before using over-the-counter fever medications.
Antibiotics: If the fever is due to a
, a doctor may prescribe an antibiotic. This will not work for viral infections, such as
or flu.
Other drugs: Doctors may prescribe different types of medication for some viral,
, or
. For example, they may prescribe antimalarials for
. Those with chronic conditions, such as
, may need ongoing treatment with drugs to reduce the symptoms.
Hospital treatment: For severe infections or symptoms, a person may need hospital treatment. Doctors may provide IV fluids, IV antibiotics, equipment to help a person breathe, or other interventions.
Sometimes, young children with a high temperature have
. This is most likely to occur between the ages of
.
While febrile seizures can be alarming, they often result from
,
, or a respiratory virus, and are not usually serious.
Still, caregivers should seek medical advice if this occurs and remain watchful for any signs of a more serious infection.
Less commonly, febrile seizures may stem from a more severe illness, such as
, a
, or pneumonia.
There are two types of febrile seizure:
Simple febrile seizures
This type of febrile seizure can last from a few seconds to 15 minutes. However, it usually lasts less than 5 minutes and does not occur again during a 24-hour period. Around
of febrile seizures are of this type.
A simple febrile seizure typically involves the whole body. The symptoms include:
stiffness in the body
twitching in the arms and legs
eyes rolling back
a loss of consciousness while the eyes stay open
There may also be:
irregular breathing
urination, defecation, or both
vomiting
Complex febrile seizures
This type of febrile seizure lasts longer than 15 minutes, comes back more often, and tends to affect only a part of the body, rather than the whole body.
Complex febrile seizures are more serious than simple febrile seizures. A child who has a complex febrile seizure is more likely to experience
as they grow older.
Around
of children who have either type of seizure will have other similar seizures at a later date.
What to do
If a child has a febrile seizure:
to determine how long the seizure lasts.
Protect their head with something soft.
Remove any potentially dangerous objects from nearby.
Place them on their side in the
and check that nothing is obstructing their breathing.
During a seizure, do not try to:
hold the child still
put anything in their mouth
give the child a bath to cool them down
Next, contact a doctor, call 911, or go to the nearest emergency room. The doctor may suggest managing the child’s temperature with medication and ensuring that the child drinks plenty of fluids.
To prevent a fever, people can take steps to avoid getting infections. This includes:
washing the hands regularly with soap and water, or using
if this is not available
not touching the face with unwashed hands
cleaning and disinfecting surfaces regularly
avoiding close contact with people who are unwell
staying up-to-date with vaccinations
A fever is usually a symptom of an infection. It is not usually a cause for concern, but the underlying illness may need medical treatment.
Often, a fever will resolve without medical attention. However, if a child or an older adult has a fever, if the individual has other severe or worsening symptoms, or if they have
, they should seek medical help.