How to take a child’s temperature: Methods and thermometers

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Several thermometer types are available for children of varying ages.

Pacifier thermometers and forehead strips may not be accurate. They can function as screening tools, but the readings they give may differ from the child’s actual temperature.

The same is true for axillary readings, taken by placing a thermometer under a child’s armpit.

Glass mercury thermometers can break and leak, so they are not a safe choice for children or the environment.

Clean the thermometer before and after use with rubbing alcohol or room-temperature water. Using water that is too warm or cold may affect the thermometer reading.

Rectal

A rectal temperature is the most accurate, particularly for infants age 3 months or younger.

Labeling a thermometer for rectal use ensures that no one will use it for an oral temperature reading.

Here is how to use it:

1. Apply a small amount of lubricant, such as petroleum jelly, on the end of a digital thermometer.
2. Position the child on their belly or on their back with their legs folded against their chest.
3. With the thermometer powered on, gently insert it 1.3–2.5 centimeters (0.5–1.0 inch) into the child’s rectum. Stop if there is resistance.
4. Hold the thermometer in place until it beeps, then gently remove it.
5. Read the temperature and repeat if required.

Oral

Designate a thermometer for oral use only and label it accordingly, so that nobody uses it for a rectal reading.

An oral thermometer is useful only if a child can close their mouth as instructed and keep it closed for the time required to obtain a reading.

Here is how to use it:

1. Wait 15–30 minutes after a child has eaten or drank.
2. Turn on the thermometer.
3. Place it under the child’s tongue, on one side and toward the back of the mouth.
4. Instruct them to close their mouth without biting, and to keep their lips together.
5. Hold the thermometer in place until it beeps, then remove it from the child’s mouth.
6. Read the temperature and repeat if required.

Tympanic

Young infants have narrow ear canals, so the tympanic temperature method is better for children age 6 months or older.

Here is how to use it:

• Wait at least 15 minutes after a child has come indoors if they were outside.
• Turn on the thermometer.
• For a child under 1 year of age, pull the outer ear back.
• For a child over 1 year of age, pull the outer ear back and up.
• Gently insert the thermometer probe into the outer ear canal.
• Hold the thermometer in place until it beeps, then remove it from the ear.
• Read the temperature and repeat if required.

Forehead

Forehead thermometers measure the temperature of the temporal artery, located on each side of the head near the temples.

Check the thermometer package instructions for specifics about how to obtain this type of reading.

One method is as follows:

1. Place the thermometer on the child’s forehead.
2. Press and hold the scan button.
3. Slide the thermometer horizontally across the forehead while maintaining contact with the skin.
4. Stop when the thermometer reaches the child’s hair and release the scan button.
5. Read the temperature and repeat if necessary.

The typical range for a child’s body temperature is 96.8–100.3°F (36–37.9°C).

According to the American Academy of Pediatrics, a temperature of 100.4°F (38°C) or higher means the child has a fever.

Fever is not a condition itself. Instead, it is usually a sign that a person’s body is responding to something else. A child’s temperature can increase for a variety of reasons.

They may have a viral or bacterial infection such as:

• a common cold
• a urinary tract infection (UTI)
• an ear infection
• gastroenteritis
• measles
• mumps
• chickenpox
• scarlet fever
• sixth disease (roseola)
• pneumonia
• meningitis
• appendicitis
• a joint or bone marrow infection

Infection is not the only cause of fever. A child can also experience an increase in body temperature due to:

• physical activity
• excitement
• clothing that is too warm
• teething
• vaccination
• dehydration
• hives
• sunburn or sunstroke
• metabolic or rheumatic disease
• allergic reactions to food or medication

Fever often goes away on its own when the underlying cause has resolved. However, sometimes parents and caregivers may need to take their child to see a doctor.

A child with a fever should seek medical attention if they have:

• a temperature higher than 102°F (39°C)
• a temperature higher than 100.4°F (38°C) and are under 3 months of age
• a fever that comes and goes
• a seizure
• a fever lasting 4 days or longer
• a stiff neck
• a severe sore throat or headache
• confusion
• excessive drowsiness
• abdominal pain, diarrhea, or vomiting
• a skin rash
• worsening symptoms
• unusual behavior
• heightened irritability
• prolonged insufficient fluid intake
• another condition, such as cancer, or an immune system issue, such as sickle cell disease

Here are two frequently asked questions about taking a child’s temperature.

Do you add a degree when taking a temperature under the tongue?

When someone takes them correctly, oral temperatures are accurate and do not need adjustments.

Do you add 1 degree under the armpit?

Axillary temperatures may be lower than readings from other methods. A child’s core body temperature is generally higher than a reading obtained from under the armpit.

How to take a child’s temperature can depend on the age of the child. For example, children younger than age 4 years should not use an oral thermometer.

Common methods for taking a child’s temperature include rectal, oral, ear, and forehead.

Tools like temperature-taking pacifiers and forehead strips are not as accurate as thermometers and serve as screening tools only.