How to take the temperature ?

The different methods

There are several more or less reliable and practical ways to take your child’s temperature:

Rectal route (through the rectum),
Axillary track (under the armpit),
Oral route (through the mouth),
Ear canal (by the ear),
On the temporal artery (on the forehead).

Depending on the selected technique, normal temperatures vary according to the following ranges:

Rectal: 36.6°C to 38°C / 96.8°F to 104°F
Axillary: 34.7°C to 37.3°C / 93.2°F to 98.6°F
Earwig: 35.8°C to 38°C / 95°F to 104°F
Buccal: 35.5°C to 37.5°C / 95°F to 98.6°F

The way you take the temperature depends on your child’s age. The following table will help you choose the best method.

Age	Recommended method
From birth to 2 years old	First choice : Rectal 2e choice : Axillary
From 2 to 5 years old	First choice : Rectal 2e choice : Axillary, Auricular
More than 5 years old	First choice : Mouth 2e choice : Axillary, Auricular

Rectal thermometer

The rectal thermometer is the reference tool, as it is the measurement site where the body temperature is highest. However, this technique has a number of disadvantages:

Its invasive nature: it is in fact poorly tolerated by many children, and little appreciated by parents,
Its thermal inertia: the rectum reflects variations in the central temperature with a delay of 30 to 45 minutes,
Its accuracy depends on the depth at which the thermometer is inserted,
The presence of stools can disrupt measurements.

Some risks must be taken into account: rectal perforations have already occurred, and without proper sterilization techniques, rectal thermometry can spread contaminants often contained in the stool.

Axillary thermometer

Used in first-line maternity, the axillary thermometer is easier, more hygienic and just as reliable as a rectal thermometer. It is the temperature of the axillary artery that is measured with this technique. On average, the latter is 0.6 to 0.7°C lower than the rectal temperature, when the arm is properly closed. This technique is recommended by the American Academy of Pediatrics, among others, because it is practical and comfortable, regardless of the child’s age. The armpit is also the best place to continuously measure temperature with patch thermometers like Tucky.

Oral thermometer

The mouth is the most accessible place to take the temperature. However, the result can be distorted by various factors:

Recent ingestion of food or beverages,
Breathing through the mouth,
Failure to keep the mouth closed for 3-4 minutes.

The language must also be lowered during the measurement period, which is a difficult task for children to perform. This measurement method is therefore not recommended for young children.

Ear thermometer

The eardrum channel offers a very fast temperature reading, but the infrared probe of the thermometer must be able to access the eardrum directly, and several factors can disturb this access:

Presence of a earwax plug,
Eardrum too narrow (this is why this method is not recommended before the age of 2 years),
Incorrect position of the thermometer due to the child’s movements,
Use of a dirty probe, impermeable to infrared rays.

This technique will also be ineffective in cases of otitis media.

Temporal thermometer

The temporal temperature is measured with a specific infrared thermometer. This is placed at the temple level, in the extension of the eyebrow. At this point, the result is 0.2°C below rectal temperature. This measurement method is fast and convenient, but it is controversial because it requires very precise positioning and distance. It is therefore difficult to obtain good repeatability of the measurement. Therefore, when accurate measurements are to be made at home, this technique is not yet recommended.

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Sources : High Authority of Health (HAS): Read the article American Academy of Pediatrics: Read the article French Pediatric Society: Read the article Ameli: Read the article