A Guide to Selecting and Using the Most Suitable Thermometer

It is very common nowadays to have your temperature checked when entering a doctor’s office, work, or other facilities. In fact, we keep a record of the staff’s daily temperature at Community Clinical Pharmacy.

In order to choose the right thermometer, one should consider the patient’s age, ability to follow directions for use, accuracy, and cost. Ask one of our pharmacists and we will steer you in the right direction.

• Always read the instructions that come with the thermometer

• Clean the thermometer before and after each use

• To accurately monitor changes throughout an illness, patients should use the same thermometer and same site of measurement

• Temperature measurements have different normal values, based on the route used to measure

Choosing Between Thermometers

There is a wide variety of thermometers on the market. The table below describes some of the types of available thermometers, their accuracy, and pros and cons:

Rectal (digital probe thermometer)
Most accurate. Patient has a fever if rectal temperature shows ≥100.4 °F (38 °C).
Great for use in young children, especially infants <3 months of age. Caution: Potential risk of rectal injury.
Do not use the same digital thermometer for oral and rectal use.

Oral (digital probe thermometer)
Patient has a fever if oral temperature shows ≥100 °F (37.8 °C).
May be uncomfortable to keep your mouth closed long enough for a reading (about one minute).
For use in children four years or older.

Underarm/Axillary (digital probe thermometer)
Less accurate than rectal or oral routes. Patient has a fever if the axillary temperature shows ≥99 °F (37.2 °C).
Can be used in children three months and older.
Incorrect placement, movement during measurement, and inadequate duration of placement may affect accuracy.

Ear (digital tympanic thermometer)
May be more accurate than oral and axillary temperatures, if used correctly.
Patient has a fever if ear temperature is ≥100.4 °F (38 °C).
Uses an infrared scanner to measure temperature. It is safe to use.
Takes only seconds for a reading.
Not recommended in infants <6 months.
Excessive earwax, a small and/or curved ear canal, ear infections, or improper placement can affect accuracy.

Forehead (temporal artery thermometer)
Available as touch and non-touch.
If used properly, may be the most accurate alternative to a rectal thermometer. It is important to read the instructions and use them correctly. Make sure the lens is clean.
Patient has a fever if forehead temperature is ≥100.4 °F (38 °C).
Uses an infrared scanner to measure temperature. It is safe to use.
Fast. It can be used for all ages and even when sleeping.
Some can be used on the wrist, behind the ear, naval, and temple, but these sites may not be as accurate as the forehead.

Color changing strips
Not recommended, due to lack of accuracy and reliability.
Detects changes in skin temperature, but not reliable to measure core body temperature.
Available as reusable and single-use (usually more expensive).
May be helpful for a quick temperature screening.