Normal body temperatures vary depending on many factors, including a person’s age and activity levels.

The average adult body temperature is around 98.6°F (37°C). However, people’s baseline body temperature can be slightly different.

In this article, we discuss typical temperature ranges for adults, children, and those who are pregnant. We also consider factors affecting body temperature and when to call a doctor.

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Body temperature readings vary depending on where a person takes the measurements on the body. For example, rectal temperature readings are higher than oral readings, while armpit readings tend to be lower.

Body temperature readings can also vary depending on the following factors:

  • a person’s age
  • the time of day, typically lowest in the early morning and highest in the late afternoon
  • a person’s recent activity
  • food and fluid intake

According to reviews, the average adult body temperature across all different reading sites is 97.86°F (36.59°C).

Researchers also found that the average orally-taken adult body temperature falls between 97.2–98.6°F (36.24–37°C).

Average body temperature can vary across demographics. A study of almost 35,500 people found that older adults had the lowest temperatures, and African American women had higher temperatures than white men.

The researchers also found that certain medical conditions can affect body temperature. For example, people with an underactive thyroid (hypothyroidism) tended to have lower temperatures, while people with cancer had higher temperatures.

Typically, the following temperatures suggest that someone has a fever:

  • at least 100.4°F (38°C) is a fever
  • above 103.1°F (39.5°C) is a high fever
  • above 105.8°F (41°C) is a very high fever

A fever may be a symptom of COVID-19.

The average body temperature for children is around 97.52°F (36.4°C), but this can vary. As with adults, a temperature above 100.4°F (38°C) may indicate a fever in children.

Infants tend to have higher body temperatures than older children and adults. The average body temperature for newborn babies is around 99.5°F (37.5°C).

A baby’s temperature is higher because they have a larger body surface area relative to their body weight. Their bodies are also more metabolically active, which generates heat.

Babies’ bodies do not regulate temperature as well as adults’ bodies. They sweat less when it is warm, meaning their bodies hold more heat. It may also be more difficult for them to cool down during a fever.

Learn more about fever in babies here.

During pregnancy, a person’s basal metabolic rate (BMR) is higher. This means the body produces more heat.

One study found that body temperature peaks at 96–99.5°F (35.6–37.5°C) around the 12th week of pregnancy. The average body temperature reaches its lowest point of around 95.5–99.1°F (35.3–37.3°C) just after the 33rd week.

There are many types of thermometers available.

Digital thermometers

Digital thermometers are readily available and can produce accurate temperature results. A person may use these at different parts of the body.

  • Rectal measurement: Specialized digital rectal thermometers are a common option for taking the temperature of young children. A person should clean and lubricate the end of these devices before inserting them into the anus. The device will alert the user when it has made a reading and is safe to remove.
  • Oral measurement: Standard digital thermometers are simple to use orally (by mouth). First, a person must make sure the tip of the device is clean. They will then place this under their tongue toward the back of their mouth and close their lips. The device will produce a reading on an integrated display.
  • Axillary (armpit) measurement: A person can place a digital thermometer at their, or someone else’s, armpit. The arm must then remain tight to the body to ensure a good reading. This is a noninvasive option for taking a child’s temperature.

Infrared thermometers

Infrared thermometers can take temperature readings at a distance. However, these are not as accurate as other methods.

People may use tympanic thermometers to take readings from the ear canal. To use, a person will:

  • insert the device’s tip into their ear
  • align it with their ear canal
  • activate the device until it produces a result

Temporal thermometers use an infrared signal to measure a person’s temperature. The user will typically hold the thermometer a few centimeters from a person’s forehead and wait for the device to produce a reading.

One study concluded that while forehead and ear measurements are viable, nontraumatic screening options for infants, they are still not as accurate as rectal measurements.

It is important for people to always follow the instructions on the thermometer package.

If a thermometer indicates a person’s body temperature is too high or too low, they may wish to take another reading to confirm the result.

In all age ranges, a high temperature may result from short-term illnesses and usually does not cause significant harm in adults with otherwise good overall health.

If a person has a high temperature, it is important they rest and drink plenty of fluids to avoid dehydration. These at-home treatments also apply to children and babies.

In hot climates, exercise or other physical activity may cause hyperthermia — an abnormally high body temperature. Unlike infection or fever, this is typically the result of outside factors. Moving to a cooler space and taking fluids will usually remedy hyperthermia.

However, if a high temperature persists or increases, people should seek medical help.

If a person’s temperature is below 95°F (35°C) they have hypothermia and should seek medical assistance.

The need for medical assistance can vary between age groups.

Adults

In many cases, a person with a fever will not require medical attention. However, if a person has a temperature of or higher, they should contact their doctor.

A person should also seek medical assistance if they experience any of the following alongside a fever:

  • dehydration
  • lightheadedness
  • severe cramps
  • a persistent, or worsening fever

The following people should also seek medical assistance if they experience fever:

  • recent transplant participants
  • people with compromised immune systems
  • those on immunosuppressants
  • those who have recently undergone cancer treatments

If a person’s temperature is over 106.7°F (41.5°C), they have hyperpyrexia, a very high fever. This can lead to permanent organ damage and death. Hyperpyrexia requires urgent medical assistance.

If a person’s body temperature is too low, they may have hypothermia. This is a medical emergency, and they should seek assistance immediately. Doctors define hypothermia as a temperature dropping below 95°F (35°C).

Children

A person should contact emergency services if a child has a temperature over 104°F (40°C). They should also seek medical help if a child has a high temperature that lasts for 5 days or more or is experiencing dehydration, vomiting, or diarrhea.

If a child’s temperature drops below 95°F (35°C), medical assistance is essential.

Babies

If an infant 3 months or younger has a temperature of 100.4°F (38°C) or above, seek emergency medical attention. In young babies, a slight fever can signal a serious infection.

In babies up to 6 months of age, a temperature of 102.2°F (39°C) or more is also reason to contact emergency services.

As with adults and older children, if a baby’s temperature drops below 95°F (35°C), they will require immediate emergency assistance.

An area of the brain called the hypothalamus regulates body temperature. If body temperature rises above or dips below the 98.6°F (37°C) mark, the hypothalamus works to regulate the temperature.

If the body is too cold, the hypothalamus sends signals to make the body shiver, which warms the body. If the body is too hot, it sends messages to begin sweating, letting heat leave the body.

Infections cause most fevers. A fever develops as the body’s natural way of reacting to and fighting infection.

Doctors consider a fever to be a body temperature that reaches or exceeds 100.4°F (38°C). Other symptoms include:

The ideal body temperature in adults is around 98.6°F (37°C), but this varies based on age, physical activity, and health. Body temperature also changes throughout the day. A temperature of above 100.4°F (38°C) signals a fever.

Babies may have higher body temperatures than adults, but even a slight fever in babies can indicate a severe infection.

Temperature readings from different body parts give a range of body temperatures that doctors consider normal. Rectal readings are higher than oral readings, and armpit readings tend to be lower.

If a person has an unusually high or low temperature, they should seek medical attention immediately.

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