"Mummy, I feel sick!" A cry that's all too familiar to most parents. A hand on your child's forehead is a good first step when checking for fever, but for a proper measurement you'll need a thermometer.
You have several options when choosing a thermometer. The old mercury or alcohol models are hard to find these days; digital probe thermometers are safer, just as accurate, and easier to use. Other popular electronic options include ear and temple thermometers, which are simply placed in the ear or against the temple for a reading. Read our guide to find one that's right for you.
What type of thermometer do I buy?
Regardless of which type you choose, always read the instructions to ensure you know how to use the thermometer correctly and get the most accurate reading. If you're unsure, get your doctor to show you the best way to use the thermometer.
Digital probe thermometers
The most commonly available type of baby thermometer. CHOICE tests show digital probe thermometers are accurate, but some are easier to use than others due to better displays, features, instructions and ease of replacing the battery. They can be used for oral, armpit or anal readings, and usually deliver a reading in less than a minute; some take as little as 10 seconds.
Ear (tympanic) thermometers
These are inserted into the ear canal and use infra-red rays to read the body temperature. They must be carefully positioned to get an accurate reading, and have some other limitations – for instance, they aren't generally recommended for infants under six months due to the size of their ear canals. On the plus side, they are quick and less invasive than a probe thermometer. CHOICE tests show that it can be difficult to get an accurate reading with an ear thermometer.
Temple (forehead) thermometers
These use an infrared scanner to measure the temperature of the temporal artery in the forehead. They are quick and non-invasive, and are generally considered accurate, though there is some debate on this; in particular they aren't usually considered accurate for use on infants under three months. As with ear thermometers, CHOICE tests show that models of this type aren't always easy to use and aren't always accurate.
A plastic strip with heat-sensitive crystals that change colour to give a temperature reading; very easy to use, but not very accurate.
Cost: $10 or less.
These contain mercury (a silvery-grey liquid metal) or alcohol (usually coloured red). They are cheap and accurate, but nowadays more likely to be found in an old first aid kit than on a chemist's shelves. They are harder to read than digital thermometers, and there's a risk of poisoning if a they break and releases their contents.
What else do I need to know?
Most baby thermometers claim accuracy to within 0.1°C, which CHOICE tests of digital probe thermometers have confirmed. The consensus regarding ear and temple thermometers is that these too are accurate enough, though they usually don't claim to be quite as accurate as digital probes; accuracy to within 0.2°C is the typical claim. Correct usage is the key to getting an accurate reading – read the instructions or get a medical expert's advice.
Time to reading
Probe models deliver a reading in less than 60 seconds – sometimes in as little as 10 seconds. Most models wait until the thermometer reaches a stable temperature then emit a tone and display the reading, but some use a predictive method, meaning they take a partial reading and calculate the final temperature based on mathematical modelling. This makes them faster than most other models, and according to CHOICE tests, just as accurate.
Infrared ear and forehead thermometers usually give a very fast reading, often within three seconds or less, making them easier to use on a restless child.
The larger the display, the easier it is to read. Ideally it should be backlit, too.
Audible beeps indicate when the thermometer is ready to take a reading, and when it has finished.
Some models have a tone or display to show when the patient's temperature is above normal.
This is useful for comfort, particularly when taking rectal temperatures.
For protecting the thermometer when it's not in use.
These help keep the thermometer clean and hygienic – useful if you have to take readings from more than one person, though wiping the probe with sterilising alcohol between readings will also do the trick.
It's important that you, the adult user, can easily access and change the battery when needed, but you don't want your child to do that. Many digital probe and infrared thermometers use button batteries, which are very dangerous if swallowed. There's a new voluntary Safety Code for button batteries, and we hope manufacturers will use it to make their products safer. But for small devices such as thermometers, these batteries are likely to be needed for the foreseeable future. So always keep thermometers and any spare batteries well out of reach of young children and don't let them use thermometers unsupervised.