Different types of thermometer and how they measure a fever

Thermometer types & how they measure a fever

Fevers are most common in young children and babies. If you suspect your child has a high temperature, they will be warm to touch, flushed and sweating or they may have chills. Most high temperatures are harmless and a sign that the body’s immune system is defending itself from a mild illness or infection.

Nevertheless, when you suspect a fever or high temperature, especially in young babies, it can be worrying. Using a thermometer is the easiest and most reliable way of checking if they have a fever. There are many types of thermometers you can choose from, and it’s essential to find the right type of thermometer for you and your family to use. Below we look at some of the most common types of thermometers.


Forehead strip thermometer

Although they are not the most accurate type of thermometer, forehead strip thermometers are one of the least invasive types. They are a popular choice for using on young children and babies. 

To take a temperature reading using a forehead strip thermometer, hold or stick the strip to the forehead and wait for 1 minute before reading the results. For better accuracy, place the strip close to the temple and ensure the child’s forehead is dry.


Oral thermometers take reliable temperature readings from inside the mouth. This type of thermometer is more suitable for older children and adults who are able to remain still while the thermometer records the temperature


Oral thermometer

Digital oral thermometers sit under the tongue and provide accurate results within a few minutes. The thermometer will beep once the results are ready and display the temperature on a small screen. Oral thermometers can take a little longer than some other types of thermometer, so they work best for older children.

Before using an oral thermometer, ensure it has been thoroughly cleaned. Place the thermometer at the back of the mouth under the tongue and keep the mouth closed. Wait for the thermometer to beep or signal it has finished. Once there is a temperature reading the results will be displayed on the screen.


Rectal thermometer

Due to their high accuracy, rectal thermometers are usually recommended for use on newborns and young babies. They can, however, be somewhat uncomfortable, so care should be taken if using this method for taking a temperature reading. To ease comfort, use a flexible tip thermometer and apply a water-soluble lubricant.

Thoroughly clean the probe before and after using a rectal thermometer. Lay the child on their back and insert the tip of the thermometer no more ½ inch into the rectum. Wait until the thermometer beeps or indicates it has a reading, which will be displayed on the small screen.


Ear thermometer

The eardrum is an extremely accurate place to take a temperature reading, due to its location inside the head. Using an infrared sensor, ear thermometers can record the temperature of the eardrum within a few seconds. They are a popular choice for using on young children and babies who would be unable to keep still long enough for an oral thermometer. You can view our range of ear thermometers here.

Before using an ear thermometer, ensure the ear is clean and place a sterile cover over the thermometer probe. While keeping the child’s head still, press the thermometer against the ear canal, creating a seal around the probe. Wait a few seconds for temperature reading and dispose of the used probe cover.


Ear thermometers take quick and reliable


Contactless thermometer

Contactless thermometers use an infrared scanner to quickly and accurately measure the body temperature via the temporal artery located on the forehead. Contactless and non-invasive, non-touch forehead thermometers are less distressing and easy to use. They are highly recommended for young children and babies who may struggle to keep still or are sleeping when you need to take their temperature. Look out for contactless thermometers that can record several temperature readings, helping you monitor a fever or high temperature over time.

Contactless thermometers are one of the easiest methods for taking a temperature reading, and the results are almost instant. Point the scanner at the child’s forehead, and the temperature reading will show up on the screen within less than a second.


Treatment for fevers

Most fevers are harmless and will run their course within 3 or 4 days without needing any medical intervention. You should consult your doctor if your child’s fever is accompanied by other signs of illness or your child is under three months old with a temperature of 38°C or above. If your child is aged between 3-6months old and has a temperature of 39°C or above, you should also consult a doctor.

You can help treat your child’s fever by:

  • Giving them plenty of fluids
  • Checking on them regularly during the night
  • Dressing them in light clothing
  • Offer paracetamol or ibuprofen (refer to packaging before using)
Safe and Sound Health's full range of body temperature thermometers



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