Normal Body Temperature: What's a Fever & What's Not

Normal body temperature is typically around 97°F to 99°F (36.1°C to 37.2°C), although it can vary slightly depending on the person, time of day, and measurement method.

A fever is generally considered a body temperature of 100.4°F (38°C) or higher, while a temperature below 95°F (35°C) may indicate hypothermia. Normal body temperature can also vary based on where it is measured, such as under the arm, or in the mouth, ear, or rectum.

Measuring normal body temperature correctly with a thermometer is important for identifying and monitoring a fever. Knowing the normal ranges for adults and children, common fever symptoms, and ways to lower a fever can help show when medical attention may be needed.

What is normal body temperature?

Normal body temperature usually ranges from about 97°F to 99°F (36.1°C to 37.2°C), although underarm readings may be slightly lower than oral or rectal readings.

A temperature above 100.4°F (38°C) often indicates a fever, while, according to the CDC, a body temperature below 95°F (35°C) may indicate hypothermia and requires urgent medical attention.

What is considered a fever?

A fever is generally considered an armpit temperature above 100.4°F (38°C). It may be classified as:

• Slightly elevated (low-grade fever): 99.5°F to 100.2°F (37.5°C to 37.9°C). In these cases, other symptoms may occur, such as chills, fatigue, shivering, or facial flushing.

• Moderately elevated: 100.4°F (38°C) or higher.

• High fever: above 102.2°F (39°C). Medical care may be needed, especially if the fever is persistent, worsening, or accompanied by symptoms such as confusion, trouble breathing, severe weakness, dehydration, or seizures.

According to the American Academy of Pediatrics, a temperature of 100.4°F (38°C) or higher in infants and children is considered elevated, regardless of whether it is measured under the arm, in the mouth, on the forehead, or rectally.

Is 99.5°F normal or a fever?

A temperature of 98.6°F (37°C) is generally considered normal. A temperature of 99.5°F (37.5°C) is usually not considered a fever, but it may be slightly higher than your usual body temperature.

This can happen from wearing warm clothing, spending time in the sun, exercising, or taking a warm bath. However, if your temperature continues to rise above 99.5°F (37.5°C), it may be an early sign of an infection or inflammation.

It is recommended to check your temperature again later in the day, especially if you also have symptoms like pain, cough, chills, fatigue, or a general feeling of being unwell.

How to measure body temperature correctly

To measure body temperature correctly, it is important to know how to use each type of thermometer. The most common types are:

• Digital thermometer: place the metal tip under the arm, in the rectum, or in the mouth, making direct contact with the skin or mucous membranes, and wait for the beep to check the temperature.

• Glass thermometer: place the tip of the thermometer under the arm, in the mouth, or in the rectum, making direct contact with the skin or mucous membranes, wait 3 to 5 minutes, and then check the temperature.

• Infrared thermometer: point the thermometer at the forehead or inside the ear canal and press the button. After the beep, the thermometer will show the temperature immediately.

Body temperature should be measured at rest and never right after physical activity or a bath. In these situations, it is normal for body temperature to be higher, so the reading may not be accurate.

How to measure a baby's temperature

A baby's body temperature should be measured with a thermometer, just like in adults. More comfortable and faster thermometers, such as digital or infrared thermometers, are usually preferred.

The most accurate place to measure a baby's temperature is the rectum. In these cases, a digital thermometer with a soft tip should be used to avoid hurting the baby. However, if parents are not comfortable taking a rectal temperature, they can measure the temperature under the arm and have the rectal temperature confirmed by a pediatrician, if needed.

How to lower a fever

There are some natural ways to lower body temperature and relieve a fever, such as removing excess clothing, taking a lukewarm bath, or applying cool compresses to the forehead and face.

However, depending on the cause, medication may be needed. Acetaminophen is one of the most commonly used medications to reduce a fever and is typically taken every 4 to 6 hours as directed.

The dose of acetaminophen should always be determined by a healthcare provider, especially for children, as it varies according to body weight.