The most common type are the digital thermometers. These can be used at any age from birth. They are easy to use and accurate, and are usually the cheapest.

The electronic ear thermometer is expensive, and it is not suitable for use in small babies.

How to use a digital thermometer

 These thermometers are used in a similar way to the old-fashioned mercury-in-glass thermometers, but they are much easier to read. They give a digital read out. They can be used for all ages. There are a number of brands. They are usually the cheapest option. You need to read and follow the instructions that come with your one.

If your child is under five years, you can use the digital thermometer under the arm. If you measure the temperature under the arm, it records about half to one (0.5 - 1.0) degree Celsius lower than the core temperature.

To use a digital thermometer under the arm (the axillary temperature):

• turn it on (these thermometers usually have a button you press to turn on)
• place the end in the armpit against the skin, and bring your child’s arm down over the top of it. It often helps to hug your child to keep the arm down and the thermometer in place
• some thermometers beep while measuring, with a change in the beep when the core temperature is reached; others only beep when the core temperature is reached. To avoid confusion, it is worth keeping the thermometer in place for two minutes.
• remove the thermometer and read the number on the side. The temperature you read is about half to one (0.5 - 1.0) degree Celsius lower than your child’s actual body or core temperature

If your child is five years of age or older you can try to measure the temperature in the mouth (the oral temperature).

To use it in the mouth in older children:

• your child has to be able to co-operate, which usually means they are of school age
• turn it on
• place the end in the mouth under the side of the tongue. Try to get your child to keep it there
• some thermometers make beeping noises when they have finished, but it is worth keeping it in place for at least two minutes
• remove the thermometer and read the number on the side. The temperature you read in in degrees Celsius is close to your child’s actual body or core temperature

How to use an ear thermometer

The electronic or infrared ear thermometer is fast and accurate if it is used correctly. It can be used in older children but is not recommended for use in young babies.

There are a number of brands.  They are more expensive than digital thermometers.

Read the instructions for your thermometer to find out how to turn it on and take the reading. When placing the measuring end in the ear, be gentle. You do not have to push it far into the ear canal, just at the entrance.

How to use an infrared forehead thermometer

Infrared forehead thermometers are a new type of thermometer. They are quick and easy to use, as you simply point them at your child’s forehead. They are expensive and it is not clear yet how accurate they are. They measure the forehead skin temperature which changes a lot with blood flow and room temperature.

How to use a mercury-in-glass thermometer

These old style thermometers are no longer available but some households still have them. Mercury vapour can be toxic if the thermometer breaks, so consider getting a new one.

If you do use a mercury-in-glass thermometer, be very careful. You use them the same way you use a digital thermometer, except that, before using it, you hold the thermometer by the end (not the tip) and gently shake it a few times to make the mercury settle down.

Reading the thermometer takes a bit of practice.

How to use a plastic strip thermometer

These are plastic strips that you place on your child’s forehead. They are not accurate, and are not recommended.

Where to go for more information

BabyCheck www.nicutools.org/MediCalcs/BabyCheck.php3
This website tool, for babies under six months old, might help guide you as to whether you need to take your baby to a doctor. The website has been designed by a neonatal doctor. The other areas of this website (NICU Tools) are aimed at health professionals.

Telephone advice - Healthline and PlunketLine

• ring PlunketLine on 0800 933 922 if you have child health and parenting questions or queries. For example, if you have questions about such issues as parenting, crying, sleeping, your child's growth, development, behaviour, immunisation, breastfeeding, nutrition, oral health, safety or want to know more about the Well Child / Tamariki Ora programme
• call Healthline on 0800 611 116 if you need advice about a child of any age who is unwell or hurt, or has any symptoms of sickness. Healthline provides a full range of telephone triage and health advice for children (and adults)
• both services are available 24 hours and are free to callers throughout New Zealand, including from a mobile phone