Why do I need a thermometer?

You may need to measure your child's body temperature with a thermometer if you are unsure if they have a fever. A fever is temperature of 38^oC or more in a baby under 3 months of age, and 38.5^oC or more in older infants and children. There are different types of thermometers, and they have different features.

Your child's normal body temperature can vary depending on their age and the time of day.

Remember that fever is just one sign of illness, and your body temperature is not necessarily the most important measure of how sick you are. It is important that you monitor all of your symptoms and see your doctor if you are unwell.

CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

How do I measure my child's temperature?

You can take a child's temperature in a number of ways and the results can vary depending on the type of thermometer you use. Always follow the manufacturer's directions.

Some thermometers and techniques are more suitable for certain age groups. Ask your Maternal and Child Health Nurse, GP or pharmacist to show you how to use your thermometer to get the most accurate reading.

What are the different types of thermometers, and what should I choose?

Digital ‘stick' thermometers

Digital thermometers are quick to use and reasonably accurate. They can be used under the arm (in the armpit) or under the tongue.

Under the arm (axillary) digital thermometer is the preferred method for babies younger than 3 months of age.

1. Place thermometer tip in the centre of the armpit, when the skin is dry.
2. Place the baby's arm securely against their body.
3. Turn thermometer on, and leave the thermometer in place for the time stated in the manufacturer's instructions.

Under the tongue (oral) digital thermometer is useful if your child is old enough to understand how to keep the thermometer under their tongue. Oral thermometers should not be used if your child is shivering.

1. Check that your child hasn't had anything hot or cold to eat or drink for 20 minutes before you take an oral temperature.
2. Place the tip under your child's tongue, ask your child to close their mouth and lips to keep the thermometer in place.

It is important to disinfect your thermometer before and after use with an alcohol wipe.

Ear (tympanic) thermometers

Ear thermometers take the child's temperature very quickly, so they are useful if you child finds it difficult to sit still. They can be expensive and the reading may not be accurate if the thermometer is not placed correctly in the ear. Follow the manufacturer's instructions carefully to get an accurate temperature reading.

1. Gently insert the probe into ear canal with the tip facing the inside, towards the inner ear.
2. Press the thermometer button and wait for the beeps.
3. If ears have been covered (headphones/beanie), remove items and wait until ear canal is cool before you measure the ear temperature. If your baby's ear canals are too small to properly insert the probe, chose another type of thermometer.

Infrared thermometers

These use an infrared scanner to measure body temperature without direct contact with the skin. These are the easiest types of thermometers to use, but they can be inaccurate.

Strip-type thermometers

Strip-type or plastic tape thermometers placed on the forehead, are not an accurate way of taking temperature.

Mercury thermometers

Do not use mercury thermometers. Mercury-in-glass thermometers haven't been used in hospitals for some years and are generally no longer available to buy. They can break, releasing small shards of glass and highly poisonous mercury.