What the best digital thermometer has:

• Accurate temperature readings. No matter what other features it has, a thermometer that doesn’t give accurate temperature readings is useless.

• Quick results. With most digital thermometers, you or your sick child have to sit quiet and motionless until the reading is complete. Having a fast thermometer makes it easier to get through the process without repeated do-overs because you moved or let the device slip out of place. The best digital thermometers offer readings in 10 seconds or less.

• Convenient testing locations. The ideal testing location (rectal, oral, underarm/maxillary or forehead/temporal) depends primarily on the age and disposition of the patient. For children age three and under, rectal temperatures are still generally said to be the most accurate.

• A beeper and backlit display. Sometimes it’s easier to take a temperature in the dark, either to avoid waking someone else in the room or to avoid further disturbing a cranky, tired child. A backlit display and a beep-when-done feature both make the whole process a little more foolproof.

• Fever alert. Some digital thermometers offer a color-coded fever alert to let you know if you or your child have a high temperature. This takes the guesswork out of reading the display, especially if you’re feeling groggy or sick yourself.

• Memory to store prior readings. Many digital thermometers have an internal memory that stores anywhere from one to thirty previous temperature readings. This eliminates the need to immediately document temperatures taken in the middle of the night or the early morning, and also lets you go back and double-check to make sure you’ve recorded things correctly.

• Long battery life. Whether your digital thermometer uses a button cell battery or standard alkaline batteries, the longer its battery life, the less time you’ll spend fumbling to change batteries in the dark.

Know before you go

Consider the age of the patient.

Many physicians still advise using a rectal thermometer for children up to three years of age, but recommend other types of thermometers for older children and adults who will usually object to the use of a rectal thermometer. If the person whose temperature you’re taking struggles to stay still during a reading, minimize the struggle by using a faster or less-invasive thermometer.

When do readings usually take place?

For a sick newborn, parents may want to take their temperature during the night when the infant is calmer. Older children and adults may prefer to have their temperatures taken during the day. If you’re in the habit of taking temperatures at night, keep in mind that several features can affect the thermometer’s suitability, including how invasive the thermometer is and how loudly it beeps to confirm a good reading (which might wake others in the room).

Do you need to document temperatures over time?

If you’re using a digital thermometer for fertility tracking or for a chronic illness that requires ongoing documentation, look for a thermometer that stores many past readings in internal memory. Being able to store 20 or 30 readings saves you from having to constantly document your readings one at a time, especially if you’re taking temperatures at night or in the early morning.

Will you be using the thermometer for more than one person?

If you’re looking for a digital thermometer for the whole family, look for a model with disposable probe covers or an easy-to-clean probe. This is especially important if you use the same thermometer for rectal temperatures and measuring other sites, although most users quite rightly prefer to hold one thermometer in reserve for rectal measurements only, and use another one for taking temperatures at other sites.