Thermometers

Which type for which case

Digital contact. The classic. It takes longer but is the most accurate and the cheapest. For adults and older children who can stay still, nothing else is needed.

Infrared forehead. It measures in seconds without contact. Its great value is that it measures a sleeping child without waking them — and an infant who will not stay still.

Ear. Fast and reasonably reliable, but it requires correct positioning. It is not recommended for very young infants because of ear canal size.

Why readings differ

It is the most common question and has a simple explanation: every part of the body has a different normal temperature. The armpit reads lower than the mouth, and rectal reads higher.

In practice that means two things. First: do not compare readings from different sites or different devices. Second: keep the same method throughout an illness, so the comparison means something.

And for infrared: the forehead must be dry and free of sweat, and the person should have been at a stable room temperature for a few minutes. A reading taken immediately after coming in from the cold will be falsely low.

What to check

Measurement memory. Useful with a fever tracked over days — you give the doctor a picture of progression rather than one number.

Audible alert and backlight. Practical when measuring a child in the dark at night.

Battery. Check whether it is easily replaced and what type it takes. A thermometer that does not work at the moment you need it is useless.

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