What Is Body Temperature?
Your body's temperature comes from your body doing the work that keeps you alive, with most of your body's heat coming from your heart, brain, liver, and muscles.. Most of the time, your temperature will stay around the same level – though body temperature can change, depending on your activity level and time of day, among other things. When your body puts out a lot more or a lot less heat than usual, it’s trying to tell you there’s a problem.
Different Ways to Measure Body Temperature
There are several ways to measure body temperature. The best way may depend on the situation and whose body temperature is being measured.
Rectal temperature. This is the most accurate method for taking the temperature of babies and infants, especially those that are younger than 3 months old. Make sure to use a digital rectal thermometer with a short probe.
Oral temperature. You can also use a thermometer in your mouth to measure temperature. Make sure to clamp your lips together tightly and breathe through your nose.
Tympanic temperature. This is when you use a digital thermometer pointed into your ear. These thermometers are quick and easy to use, but they may not be as accurate as other methods.
Forehead temperature. You can use an electronic digital thermometer on your forehead to measure your temperature. You can also use another type of thermometer, called a noncontact infrared thermometer. Don’t use plastic strip thermometers that change color when you press them against your skin, because these are the least accurate method of measuring temperature.
Armpit temperature. You can also use any digital thermometer to take the temperature in your armpit if you don’t want a thermometer in your mouth, rectum, ear, or on your forehead. This is also called an axillary temperature.
What Are Normal Body Temperature Ranges?
Not everyone’s “normal” body temperature is the same. Yours could be a whole degree different from someone else’s. Your temperature doesn’t stay the same all day, and it will vary throughout your lifetime, too.
A German doctor in the 19th century set the standard at 98.6 F, but more recent studies say the baseline for most people may be decreasing.
Normal range of body temperature based on age
For a typical adult, body temperature can be anywhere from 97 F to 99 F. Adults over the age of 60 tend to have a lower body temperature, compared to younger adults. Babies and children have a wider range: 95.9 F to 99.5 F (if measured with an oral thermometer) or 97.9 F to 100.4 F (if measured by a rectal thermometer).
What is the normal forehead temperature for adults?
Your temperature reading may also change based on where on your body you measure it. Underarm readings can be a degree lower than what you’d find from your mouth. Rectal temperatures usually are up to a degree higher than mouth readings. If you are using a digital or noncontact infrared thermometer on your forehead, it can be slightly lower than mouth readings. But a normal temperature using a noncontact infrared thermometer will still be in the range of 97 F to 99 F for adults.
A body temperature higher than your normal range is a fever. It’s hypothermia when the body temperature dips too low. Both need to be watched.
Fever (High Body Temperature)
How high is too high when it comes to your temperature? Anything above 100.4 F is considered a fever. You may feel terrible, but on the whole, a fever isn’t bad for you. It’s a sign your body is doing what it should when germs invade. It’s fighting them off.
Fever in adults
There are different levels of severity of fevers in adults. These include:
- Low-grade fevers: 99.1 to 100.4 F
- Moderate-grade fevers: 100.6 to 102.2 F
- High-grade fevers: 102.4 to 105.8 F
If you're an adult with a fever of over 104 F, you should call your doctor.
If you have a fever, you might have other symptoms besides just feeling warm. These can include:
- Headache
- Sweats
- Chills
- Achy muscles or chest pain
- Hot, dry skin
- Nausea or vomiting
- A flushed face
- No interest in eating
Many fevers will go away within a few days. But you should call a doctor if you have any of these symptoms with a fever:
- Seizure
- Confusion or feeling sleepy or dull
- Loss of consciousness
- Stiff neck
- Trouble breathing
- Painful or burning urination
- Severe pain anywhere on your body
- A purple-spotted rash
Fever in children
Fevers in children can be tricky, and children may not be able to show that they feel uncomfortable. Signs of a fever in children can include:
- Looking red or flushed
- Feeling hot
- Feeling sweaty
- Losing their appetite
- Acting sleepy or cranky
- Complaining of a headache or body aches
Like in adults, in many cases a child’s fever can be managed at home. But you should contact your child’s pediatrician if your child is:
- Under 3 months old and has a rectal temperature of 100.4 F or higher
- Between 3 months and 3 years old and has a rectal temperature over 102 F
- Older than 3 years and has an oral temperature above 103 F
- Between 3 and 6 months old and – along with a fever – is fussier or more uncomfortable than usual, or doesn’t seem alert
- Sick enough for you to be concerned, regardless of what the thermometer says, or has a fever for longer than 3 days
How can you bring down a fever?
If you have had a high fever for 3 days or more, it is time to contact your doctor for help.
But if you have a moderate or low fever and are uncomfortable, there are some things you can try at home to bring down a fever.
- Take an anti-fever medicine, like acetaminophen or ibuprofen. Do not give a child or teenager with a fever aspirin, because it has been linked to a rare swelling in the liver and brain called Reye’s syndrome.
- Take a lukewarm bath or shower.
- Apply damp washcloths to the forehead and wrists.
- Drink fluids.
- Get a lot of rest.
Hypothermia (Low Body Temperature)
If your body loses too much heat, it can be very serious, even fatal. Hypothermia is when your body temperature goes below 95 F, and your body is losing heat faster than it can produce heat. You might think of hypothermia as something that only happens when you’re exposed to extremely cold weather for a long time. But it happens indoors, too. A below-normal body temperature can also be a sign that you’re sick.
Hypothermia in adults
Hypothermia is a special concern for the elderly. Older adults can struggle to keep their body temperature in a normal range if they’re somewhere with intense air conditioning or there’s not enough heat.
Other things can also make you more likely to get hypothermia. They include:
- Alcohol or drug use
- Hypothyroidism (an underactive thyroid)
- Anorexia
- Stroke
- Sepsis (an overwhelming infection)
- Severe burns
- Parkinson’s disease
- Nerve damage
- Malnutrition
- Medicines such as antidepressants, antipsychotics, or sedatives
- Anesthesia
- Exposure to cold weather or cold water
Whether you are indoors or outdoors, the signs of hypothermia are similar. Hypothermia causes mental confusion, so someone who is hypothermic may not be aware that they need help. Symptoms of hypothermia can include:
- Shivering (this may stop at extremely low body temperature)
- Exhaustion or feeling tired
- Confusion
- Slurred speech
- Clumsiness or lack of coordination
- Pale and cold skin
- Slowed breathing or heart rate
- Memory loss
Hypothermia in children
Hypothermia is also particularly concerning for children. Babies may not be good at controlling their temperature. They can lose heat quickly. It’s important to keep them warm. A temperature below 97 F is considered too low for babies.
Symptoms of hypothermia in babies include:
- low energy
- cold skin that looks flushed or bright red
How to treat hypothermia at home
Hypothermia is a life-threatening condition. If you suspect that you or someone that you’re with has hypothermia, you should call 911 right away or go to the emergency room.
While you’re waiting for emergency services to arrive, there are some things that you can do at home to help someone start getting warm. These include:
- Gently move the person into a warm room if you're outside.
- Remove any wet clothing the person is wearing, and replace it with dry clothing.
- If you have an electric blanket, use it to warm their chest, neck, and groin.
- You can also use skin-to-skin contact to warm someone with body heat while under loose blankets or sheets.
- If the person is alert, give them a warm beverage to drink. Do not give them any alcohol or caffeine.
- If the person is unconscious and not breathing, perform CPR until emergency services arrive. Keep trying to warm them while performing CPR.
Is 96 F a normal temperature for a kid?
If you’re measuring with an oral thermometer, the normal range for children’s temperatures is 95.9 F to 99.5 F. So 96 F would be within the normal range for a child. But for an infant, 96 F is too low. If your baby is under a year old and has a temperature below 97 F, call your pediatrician.
Things That Affect Normal Body Temperature
A lot of things can change your normal body temperature, making it higher or lower than 98.6 F. These include:
- How active you are
- What time of day it is
- The weather
- Your age
- Your sex
- If you have any medical conditions
- What you’ve eaten or had to drink
- Where you are in your menstrual cycle
- What body part or method you're using to measure the temperature (Underarm readings can be a degree lower than mouth readings, and rectal temperatures are usually up to a degree higher than ones taken in the mouth.)
Takeaways
Doctors used to think that the “normal” body temperature was 98.6 F, but we now know that there is a range of normal body temperatures for adults and children. Things including activity level, time of day, weather, age, and more can also impact your body temperature. A normal temperature for adults is in the range of 97 F to 99 F, and for children it is 95.9 F to 99.5 F. Higher temperatures than these are fevers and are caused by the body fighting off an infection. Lower temperatures can lead to hypothermia, a dangerous emergency condition.
Normal Body Temperature FAQs
What is the normal tympanic temperature range for adults? A normal tympanic (in the ear) temperature range for adults is between 95.7 F and 100 F.
What is normal toddler temperature? The normal temperature for a toddler between the ages of 1 and 3 is 95.9 F to 99.5 F, if you’re taking their temperature with an oral thermometer.
What is the normal body temperature for a newborn? The normal body temperature for a newborn is above 97 F and below 100.4 F. If your newborn falls outside of that range, take them to see a doctor right away.
