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Normal Body Temperature: What Is Considered High or Low

The normal body temperature range for teens and adults is 97–99 F. People over age 60 have slightly lower temperatures than those younger than 60.

Fever: Symptoms, Temperatures, and What to Do

A fever is when your body temperature is higher than usual, often due to an infection or illness. Doctors generally consider a fever to be an oral temperature of 100 F (37.8 C) or higher.

When you have an infection or illness, your body releases substances that tell its temperature regulator (located in the brain) to adjust to a higher setting, raising your body temperature.

A fever is when your body temperature is higher than usual, which is generally considered an oral temperature of greater than 100 F (37.8 C). It often happens because of an infection or illness. The body’s normal temperature is usually defined as around 98.6 F.

What Is ‘Normal’ Body Temperature?

The body’s normal temperature is usually defined as around 98.6 F. But the reality is that a “normal” body temperature can fall within a wide range, from 97 F to 99 F. This number changes due to your hormones, activity levels, sleeping and waking up, and other things that happen in your body in 24 hours.

Your temperature is usually lower in the morning and goes up during the day. It peaks late afternoon or evening, sometimes by as much as 1 or 2 degrees.

You don’t need to take your temperature regularly if you’re healthy. But you should check it more often if you feel sick or think you might have come into contact with an illness such as COVID-19.

The Myth of 98.6

The 98.6 F standard dates to the mid-1800s. German doctor Carl Wunderlich measured the armpit temperatures of about 25,000 people and came up with an average of 98.6 F.

Newer research suggests that the number has since gone down. In a recent review, scientists looked at temperature records from three time periods spanning about 160 years. The average oral temperature slowly fell by about 1 degree to 97.5 F. A person’s age, gender, or weight didn’t make a difference, nor did the time of day.

Doctors have several ideas about why body temperatures are falling. They include:

Lower metabolic rates. Your body uses energy so all your systems can work the way they should. This creates heat. But people may have lower metabolic rates now because we weigh more than people did centuries ago. The less heat your body makes, the lower your temperature.
Lower rates of infection. In the 19th century, infections such as tuberculosis, syphilis, and long-term gum disease were more common. As a result, many people had higher body temperatures.
Better thermometers. We may have more accurate thermometers than people did a century ago.

Despite the new research, doctors generally don’t consider you to have a fever until your temperature is at or above 100 F. But you can be sick if it’s lower than that.

Over-the-counter medicines like acetaminophen, aspirin, ibuprofen, and naproxen, which are fever reducers, might hide a high temperature if you take them for another symptom like pain.

Types of Fever Patterns

Doctors use different names to describe fevers based on how they happen.

Intermittent fever

With intermittent fever, the temperature goes up but then returns to normal daily.

Remittent fever

Though your temperature falls each day with this type, it doesn’t return to normal.

Continuous or sustained fever

Your elevated body temperature stays high and only changes by a few degrees in 24 hours.

Hectic fever

Hectic fever causes big swings in temperature and usually comes with chills and sweats.

Relapsing fever

Relapsing fever causes episodes of serious rise in your body temperature, with periods of normal temperature in between that can last for days or weeks.

What temperature is a fever?

Fever can be grouped into low-grade, mid-grade, high-grade, and hyperthermia.

Low-grade. You have a low-grade fever when your body temperature ranges from 99.1 to 100.4 F. Having a low-grade fever might mean that your immune system has, to an extent, been activated.

Moderate-grade. Your doctor might describe your fever as moderate-grade if it falls between 100.6 to 102.2 F. Adults with chronic health conditions, like heart or lung problems or dementia, may notice their symptoms worsen when they have a moderate-grade fever.

High-grade. A body temperature that falls between 102.4 and 105.8 F is a high-grade fever. Sometimes, you can have a high fever from only a cold or other viral infection.

Hyperthermia. This is a fever over 105.8 F. It happens when your body temperature jumps so high because your body’s temperature regulator can’t handle how hot your environment is. Hyperthermia may show up as heat syncope or dizziness, heat cramps, heat exhaustion, and heat stroke. It can also happen when you have a life-threatening complication from an infection called sepsis or as a side effect of a medication.

Fever Symptoms

When you have other symptoms with fever, it’s usually because of the condition causing it. Other symptoms you might have when you have a fever include:

Feeling cold and shivering
Headache
Body pain
Sweating
Increased heart rate
Tiredness
Having flushed or hot skin

If you’re an older adult, serious infections tend to cause symptoms such as confusion or weight loss rather than fever. Doctors consider a temperature that’s 2 degrees higher than usual to be a sign of infection.

Children may show other symptoms like

Being unable to eat or drink
Having pain in their ears
Feeling too thirsty
Not peeing as much as they used to
Looking pale or flushed

Fever Causes

Most cases of fever happen when you have an infection. Your body is trying to fight off the virus or bacteria that caused the infection.

Most bacteria and viruses survive when your temperature is normal, but surviving becomes tougher for them with a fever. Your immune system also becomes activated to fight off the germ when you have a fever.

If you have a fever that lasts for 4 days or less, it’s likely caused by an infection. If your fever sticks around for a while or keeps coming back, it’s more likely to be caused by something else.

These causes include:

Medicines, like anti-seizure and blood pressure medicines, or antibiotics
Certain types of cancer
Heat illnesses like heat stroke and heat exhaustion
Teething in children
Some vaccines given to children
Autoimmune or inflammatory diseases like inflammatory bowel disease (IBD)

How to Take Your Temperature

A thermometer is the only way to know that you have a fever. Touch tests and skin pinching aren’t reliable. Rectal thermometers, which go into your rear end, are the most accurate, but they can be uncomfortable. Armpit, ear, and forehead thermometers aren’t as accurate. Most doctors think an oral thermometer — which you hold under your tongue — is best. Don’t use an old glass thermometer. These contain mercury, which is dangerous.

Before you use an oral thermometer, wash your hands with soap and warm water. Don’t eat or drink anything for at least 5 minutes before you take your temperature. Put the tip of the thermometer under your tongue. Keep your mouth closed. After about 30 or 40 seconds, the thermometer will beep. That means the final reading is ready. Oral thermometer temperatures are about 1/2 to 1 degree cooler than rectal ones. When you’re done, rinse the thermometer in cold water, clean it with alcohol, and rinse again.

If you have a child younger than 3, a rectal thermometer may be easier and more accurate. Put a small amount of lubricant like petroleum jelly on its tip. Have your child lie on their belly, and insert the thermometer into their bottom until the tip is completely inside. Don’t force it. When you hear the beep, after about 30 seconds, remove it. Check it and then clean it again.

How to Break a Fever

A fever is a sign of your body fighting off an infection. As the actual fever isn’t harmful, there’s conflicting opinion about whether a fever needs to be treated.

However, if your fever is higher than about 105.8 F or you have health conditions like lung disease, heart disease, or dementia, you need medication to break the fever.

Medications for fever

Medication won’t get rid of the infection quicker, but it can help with the discomfort that comes with a fever.

If your fever is higher than 101 degrees or is making you uncomfortable, you can try an over-the-counter medication.

These fever-reducing medicines include:

Acetaminophen
Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen

If your child has a fever of 100.4 F or higher or they don’t feel well, you can try children’s doses of acetaminophen or ibuprofen. Follow the recommended dose on the medicine information leaflet.

If the fever lasts longer than 3 days, or if your child is 3 months of age or younger with a fever of 100.4 or higher, get medical treatment immediately.

Don’t give your child aspirin, as it can cause Reye syndrome, a serious condition that causes swelling in the liver and brain.

Home remedies for fever

You can cool down your body temperature using cooling blankets and dressing lightly, for example, if your temperature is high.

Drinking plenty of fluids, resting, and having a lukewarm bath may also help to bring body temperature down.

Fever in Babies

Your baby has a fever if their temperature is 100.4 F or higher. In infants 3 months old or younger, seek medical care right away.

Usually, a fever is not a cause for concern. Only about 1 out of 100 fever cases in children are tied to a serious health condition, like pneumonia. Most cases are due to a harmless virus that their bodies can handle alone, and they’ll feel better within 2-3 days.

When your child has a fever, they may look tired and pale. Their forehead and neck can be hot. They may cry more and not want to eat or drink anything.

Take your child to a doctor immediately or call 911 if they have symptoms like:

Fever of over 100.4 F
Fever that comes and goes
Fever that lasts for more than 3 days
Febrile seizure or convulsion
Stiff neck
Restlessness
Confusion
Vomiting
Diarrhea
Stomach pain
Skin rash
Worsening symptoms since last doctor visit
Refusal to eat or drink

When to Call a Doctor for a Fever

If your temperature is between 100 and 102, drink plenty of fluids and rest. You can take a fever reducer if you like.

Calling a doctor for fever in adults

Call your doctor if your temperature is over 102 F and it doesn’t go down within 1-2 hours after you take a fever-reducing medication.

If you have a fever with a cough or shortness of breath and think you might have come into contact with someone who has COVID-19, call your doctor to talk about the next steps.

Always call your doctor if you have any kind of fever along with a severe headache, a stiff neck, throat swelling, or confusion. They may be signs of a serious condition, such as strep throat or meningitis.

Even if you don’t have these symptoms, your doctor may tell you to take your temperature at certain times, like first thing in the morning or at night. You can record the readings and report back.

Calling a doctor for fever in children

In children, call a doctor immediately if your child is:

Upset and can’t be calmed down
3 months of age or younger with a fever of 100.4 or higher (seek emergency care)
Younger than 2 years of age with a fever of 100.4 or higher lasting more than 1 day
2 years old or older with a fever of 100.4 that lasts longer than 3 days
Any age and has repeat fevers of above 104 F

Fever Complications

Fever over 105.8 F left untreated can cause complications like organ malfunction, organ failure, and death.

See a doctor immediately if you have a high fever with symptoms like:

Difficulty breathing
Thinking problems
Confusion
Severe chest or stomach pain or headache
Stiff neck
Pain when peeing
Convulsions or seizures
Rashes or bruises
Loss of consciousness
Discharge when peeing
Swelling

Moderate fevers can worsen symptoms in people with lung or heart diseases, as it raises breathing and heart rate. It can also worsen symptoms in people with dementia.

Fever can also cause febrile seizures in children, typically between 6 months and 5 years of age. But they most often happen between 12 and 18 months of age. These seizures are usually harmless and stop within a minute or two. Some may happen for only a few seconds. In some cases, they can last for more than 15 minutes.

Takeaways

Fever is usually a sign that your body is fighting an illness. But it may also happen when you have chronic conditions like autoimmune diseases and cancer or as a medication side effect. The fever often goes away on its own, but you can break it by taking over-the-counter medicines like acetaminophen or ibuprofen. See a doctor if you have a high fever and a fever that doesn’t go away within 5 days. If your child has a fever, emergency care may be needed, depending on their age. Also, see a doctor immediately if you have other symptoms like breathing problems, body pains, headache, and stiff neck.

Fever FAQs

Can allergies cause a fever? No allergies don’t cause fever. If you’re having allergy-like symptoms like a runny or stuffy nose with a fever, you might have a sinus infection.

What’s a fever dream? A fever dream is a strange dream that you may have when you have a fever. It often involves negative emotions and fewer characters and interactions.

What’s considered a fever in children? In children, a temperature at or above 100.4 F taken rectally, 99.5 F taken orally, or 99 F taken under the arm is considered a fever.

What does a fever feel like? When you have a fever, you may feel hot inside and out. You may also feel chilly and cold and have aches all over.

What does fever mean? A fever means that your body temperature is higher than usual.

What is a low-grade fever? A low-grade fever is a high body temperature ranging from 99.1 to 100.4 F.

Normal Body Temperature: What Is Considered High or Low?

The human body’s normal temperature was long considered to be 98.6 degrees Fahrenheit. Normal adult body temperatures actually range from 97 to 99 F. Plus, there’s some evidence to suggest normal temperature has decreased over time and is closer to 97.9 F.

Your temperature can fluctuate and vary based on your age and the method used to measure your temperature. A fever is when your body temperature is higher than normal. Most healthcare providers consider a fever to be at 100.4 or higher.

Illustration by Michela Buttignol for Verywell Health

Normal Body Temperature Range

The average human body temperature is 98.6 F (or 37 degrees Celsius). However, this is just an average and varies among people. Several factors can affect body temperature, including age, sex, and where on your body you take it.

Across a person’s lifespan, healthy, normal body temperature ranges in degrees Fahrenheit from 96 to 99.9.

Infants and Children

A baby or child’s normal temperature varies based on age as follows:

Preterm newborns: 97.7–98.6 F
Term newborns: 97.2–99.9 F
Babies less than 6 months old: 97.2–99.4 F
6–12 months: 96–99.7 F
1–13 years: 95.9–99 F

Adults

The normal body temperature range for teens and adults is 97–99 F. People over age 60 have slightly lower temperatures than those younger than 60.

Different Ways to Measure Body Temperature

Body temperature differs based on where on your body you take your temperature.

Central temperature measurement sites include the rectum (anus), which is a more invasive site typically used for young infants or people who are severely ill. Urine may be close to your core temperature when using an internal Foley catheter with a sensor, for example. But method matters, and excreted urine is cooler when measured outside the body.

Peripheral sites include oral (mouth), axillary (armpit), temporal (forehead), or tympanic (ear). Environmental temperature can influence these areas, so they are slightly less accurate than central sites. However, they are more accessible and practical for daily use.

Oral

Oral temperatures are taken in the mouth. The room temperature, hot or cold liquids, and probe placement can influence oral temperatures. One study showed a variation of 3.6 degrees between oral and rectal temperatures. Normal and average oral temperatures are as follows:

Normal range: 96.3–99.3 F
Average: 97.8 F

Tympanic

Tympanic (ear) thermometers are fast and easy to use. They can vary a couple of degrees between ears and in comparison to a rectal temperature. These are normal and average tympanic temperatures:

Normal range: 96.4–99.5 F
Average: 97.9 F

Axillary

Axillary temperatures are taken under the arm. They are affected by the external environment and vary from rectal temperatures. Normal and average axillary temperatures are as follows:

Normal range: 95.1–98.4 F
Average: 96.7 F

Rectal

Rectal (in the anus) temperature most accurately measures the core temperature. It is typically about 1 degree higher than oral readings. Healthcare providers commonly use rectal temperature measurements for babies less than 3 months old. These are the normal and average rectal temperatures:

Normal range: 97.3–99.9 F
Average: 98.6 F

Forehead

Temporal (forehead) temperatures can be measured quickly and easily. Temporal thermometers measure infrared heat waves coming off the temporal artery located in the forehead. However, a forehead temperature is often 0.5 F to 1 F lower than an oral temperature.

Fever During Pregnancy

It’s normal to have a slightly elevated temperature during pregnancy. But, you should report a fever (temperature over 100.4 degrees) to your healthcare provider. A fever could indicate an illness such as the flu or COVID-19. Your healthcare provider may want to order tests, prescribe medications, or monitor you carefully.

High Body Temperature (Fever)

A fever occurs when your body temperature is higher than normal and is usually a response to a disease or illness. Fevers are graded as mild, high, and very high as follows:

Elevated body temperature: 99.5–100.4 F
Low-grade fever: 100.4 F or higher
High-grade fever: 103 F
Very high or dangerous: Above 105 F

The following is how a fever is defined in children based on where the temperature is taken:

Guidelines for seeking medical attention, based on age, are as follows:

3 months or younger: Rectal temperature over 100.4 F
3–12 months: 102.2 F or higher
12 months to 2 years: 103 F or higher, despite treatment or any fever that lasts longer than 24–48 hours
2 years and older: 103 F or higher, despite treatment or any fever lasting longer than 48–72 hours

When Is a Fever Considered a Medical Emergency?

In children ages 1 year or older, seek emergency medical attention for a fever rising above 103 degrees despite treatment. Getting medical attention before temperatures reach 105 degrees is crucial because it becomes more dangerous after 105. Treating temperatures before they reach 105 typically leads to better outcomes.

Symptoms of Fever

Symptoms of a fever can be constant or intermittent (come and go). They include:

Feeling warm or hot
Skin warm to touch
Flushed face
Tired eyes
Chills

If the following symptoms occur along with a fever, they could indicate an underlying health problem that requires medical attention:

Malaise (generally feeling unwell), especially if occurring with a fever
Decreased urine output or dark urine
Persistent nausea or vomiting
Persistent constipation or diarrhea
Headache
Aching
Confusion
Stiff neck
Fever that has persisted for more than 48 hours

Regardless of their body temperature, the following signs and symptoms indicate an infant, child, or nonverbal adult should receive medical attention:

Behavioral changes (such as being less alert, not smiling, not playing, prolonged extreme fussiness or agitation)
Decreased appetite or refusing food
Abnormal skin color
Decreased urine output
Changes in bowel pattern
Breathing difficulties
Passing out
Seizures

Treating a Fever at Home

These remedies may help treat a fever at home:

Drink plenty of fluids, including water, ice pops, soup, and gelatin.
Take over-the-counter (OTC) fever-reducing medications such as Advil or Motrin (ibuprofen) or Tylenol (acetaminophen).
Place a cool towel under the arms, behind the neck, and on the forehead.
Take a lukewarm (not hot, but not overly cold) bath.
Keep the room temperature comfortable, not overly hot or cool.
Remove excess clothing or blankets.

The following are safety considerations when treating a fever at home:

Avoid giving medications to infants 3 months or younger before calling your child’s provider.
Do not use ibuprofen in children 6 months or younger.
Do not give aspirin to a child unless your child’s provider tells you to. It can cause a serious illness called Reye’s syndrome.
Avoid bundling with multiple blankets or jackets, even if you, another adult, or a child has the chills.
Do not use cold baths, ice, or alcohol baths as they can cause shivering and increase core body temperature, which can be dangerous. Lukewarm baths are fine and helpful.
Avoid too much sugar when taking in fluids.
Do not force food on someone who is refusing it.

Low Body Temperature (Hypothermia)

While people often are concerned with elevated temperatures and fevers, it’s important to note that low body temperatures could also be just as concerning. Hypothermia can be life-threatening if left untreated.

Hypothermia may be categorized into three stages:

Mild hypothermia: 90–95 F
Moderate hypothermia: 82–90 F
Severe hypothermia: Lower than 82 F

Common causes of hypothermia include:

Being in cold environments without enough protective clothing
Falling into a cold body of water
Heavy exertion, not drinking enough fluids, or not eating enough in cold weather

A low body temperature in young infants can also be caused by a serious illness called sepsis. A rectal temperature is the most accurate for infants younger than 3 months old.

Symptoms of Hypothermia

Symptoms of hypothermia include:

Confusion
Drowsiness
Pale and cold to touch
Slowed breathing
Slowed heart rates
Shivering (then lack of shivering)
Weakness and loss of coordination
Stiff body with rigid muscles

Treating Hypothermia at Home

If you suspect someone has hypothermia, call 911 or seek emergency medical attention. While you wait for help to arrive, you can take the following steps to warm the person slowly:

Move the person to a warm room if you are outdoors.
Remove any wet clothing and replace them with dry clothing (including socks, gloves, and hat).
Use a warming blanket or warm compresses on the neck, chest, and groin. You can use skin-to-skin contact under loose blankets.
If the person is alert, offer small sips of a warm liquid, such as water or broth. Avoid alcohol and caffeine.

If a person is unconscious and not breathing, perform CPR until emergency help arrives.

What Affects Body Temperature Readings?

As mentioned above, age, temperature measurement site, and the time of day factor into your normal body temperature. Sex also plays a role. People assigned female at birth tend to have higher temperatures. This also fluctuates during their menstrual cycle, ovulation, and pregnancy.

Other factors include:

Physical activity
Stress or other strong emotions
When you eat
Heavy clothing or blankets
Hot or humid environments
Health conditions, including hypothyroidism, autoimmune disorders, and some types of cancer
Immunization (children may respond with a low-grade fever)
Teething (elevated temperature, not usually higher than 100)
Some medications

Summary

The average human body temperature is 98.6 degrees F. Healthy, normal body temperatures range from 96 to 99.9 and vary across the lifespan. Several factors can affect body temperature, including age, sex, and where on your body you take it.

A body temperature over 100.4 is considered a low-grade fever; temperatures above 103 are a high-grade fever; and temperatures over 105 become more dangerous, especially if untreated. Infants three months or younger with a rectal temperature over 100.4 should see a healthcare provider.

That said, low body temperatures (below 95 F) are just as concerning and should be treated accordingly. If you suspect someone has hypothermia, seek emergency medical attention and take appropriate steps to start warming their body slowly and safely.

A Word From Verywell

Causes of fever can be as benign as having the flu or something more serious. Most, but not all, fevers are caused by bacterial infections and are usually treated successfully with antibiotic therapy. Viral and fungal infections can also cause a fever and may require anti-viral or anti-fungal therapy. Fever caused by infection, if not adequately treated, can sometimes turn into a life-threatening condition called sepsis. Therefore, all fevers should be properly identified and treated to prevent worse outcomes.

19 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

National Library of Medicine (NIH). Fever.
National Library of Medicine (NIH). Body temperature norms.
Harvard Health Publishing. Time to redefine normal body temperature?
Johns Hopkins Medicine. Fever.
Chiocca, EM. Normal vital signs in infants, children, and adolescents. Advanced Pediatric Assessment 3rd Edition. Springer;2019:578
Geneva II, Cuzzo B, Fazili T, Javaid W. Normal body temperature: A systematic review. Open Forum Infectious Diseases. 2019;6(4). doi:10.1093/ofid/ofz032
UpToDate. Patient education: Fever in children (beyond the basics).
American Academy of Pediatrics. Is a temperature ever normal?
Wise J. Rectal thermometer should be used for accurate temperature reading, analysis finds. BMJ. 2015;351:h6125. doi: 10.1136/bmj.h6125
Kaiser Permanente. Fever temperatures: Accuracy and comparison.
Mily S, Akter K, Jabin N, et al. COVID-19 infection in pregnancy: A review. Infect Disord Drug Targets. 2022;9(9):4536-4540. doi: 10.2174/187152652266622010511135
Waller DK, Hashmi SS, Hoyt AT, et al. Maternal report of fever from cold or flu during early pregnancy and the risk for noncardiac birth defects, National Birth Defects Prevention Study, 1997-2011. Birth Defects Res. 2018;110(4):342-351. doi:10.1002/bdr2.1147
National Library of Medicine (NIH) National Center for Biotechnology Information. How is body temperature regulated and what is fever?
Centers For Disease Control and Prevention. Reporting: Symptom definitions.
Zafren K. Accidental hypothermia in adults: Clinical manifestations and evaluation. UpToDate.
Penn Medicine. Hypothermia.
Perry MC, Yaeger SK, Noorbakhsh K, Cruz AT, Hickey RW. Hypothermia in Young Infants: Frequency and Yield of Sepsis Workup. Pediatr Emerg Care. 2021 Aug 1;37(8):e449-e455. doi:10.1097/PEC.0000000000001674.
American Red Cross. Hypothermia.
MedlinePlus. Pregnancy – identifying fertile days.

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