Depending on the brand, the features of ear thermometers can vary. Some come with a pre-warmed tip to prevent discomfort during insertion. Some say that this tip helps ensure accuracy, as probes can cool after being removed from the ear.

Some concerns about accuracy surround this instrument. Large amounts of ear wax buildup may interfere with its results during use. Some scientists postulate that the device may not provide accurate readings if a patient has an ear infection as well. Ear thermometers may not be helpful in diagnosing ear infections, either. Some people report variations in temperature between left and right ears.

The ear thermometer can also generally vary in accuracy up to half a degree. Though not considered an amount for alarm in adults, infant temperature, particularly in newborns under two months of age, typically has to be very specific for an accurate diagnosis. Some studies also indicate that the younger a patient is, the less accurate an ear thermometer reading will be. Doctors recommend that rectal thermometers continue to be used when ascertaining a baby's temperature.

If a child's ears are too small to accommodate an ear thermometer, do not force the probe. This can result in an injury. Doing so is also unlikely to provide an accurate reading.