April 10, 2023

Heat Check: How To Take Your Temperature

You can use a digital, tympanic or temporal artery thermometer

Person taking temperature of child using ear thermometer.

Growing up, your parent may have kissed or placed their hand on your forehead to see if you had a fever. While those gestures may have been endearing and comforting, they weren’t very accurate or scientific. (Sorry, mom and dad.)


Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

That’s why a thermometer — whether it’s a digital thermometer or a tympanic thermometer — has been the go-to way to know if you or your loved ones have a fever. Checking your body’s temperature with a thermometer is an easy and accurate method to see if a fever is present.

A fever, which is a rise in your body’s temperature, is usually caused by an infection. Though fevers can be uncomfortable, they’re a sign that the body is fighting off infection.

Internist Daniel Sullivan, MD, explains how to take a temperature, the different thermometer options and how to clean one.

Temperature ranges

So, what should your temperature be?

A normal body temperature is about 98.6 degrees Fahrenheit or 37 degrees Celsius. A normal temperature often varies from 1 to 2 F (.5 to 1 C).

“A normal temperature is usually lower in the morning and increases during the day,” explains Dr. Sullivan. “It reaches its high in the late afternoon or evening.”

In adults, a fever is considered to be a temperature of 100.4 F (38 C) or above.

“You can treat this at home with a fever reducer medication and fluids to make yourself more comfortable, or let it run its course,” says Dr. Sullivan.

But if your fever reaches 102 F (38.8 C) or higher and home treatment doesn’t lower it, it’s time to call a healthcare provider.

For kids, a fever is when their temperature is higher than 100.4 F (measured rectally), 99.5 F (measured orally) or 99 F (measured under their arm). If their fever last more than five days or is higher than 104 F (40 C), call their healthcare provider.

Types of thermometers

When using any kind of thermometer, make sure you read and follow the instructions that come with it.


“If your thermometer uses batteries, check them,” advises Dr. Sullivan. “You might notice that weak batteries give inconsistent readings.”

There are many different types of thermometers you can use to measure temperature such as:

  • Digital thermometer. A digital thermometer is the most accurate thermometer and quickest way to take a temperature. Digital thermometers are available in most drug stores and supermarket pharmacies. Depending on where you shop, a digital thermometer can cost from $6 to $20. You can use a digital thermometer to take an oral temperature, armpit temperature and rectal temperature.
  • Tympanic thermometer. This type of thermometer measures the temperature inside the ear by reading the infrared heat there. For older babies and children, ear thermometers can be quicker and easier to use. But they aren’t recommended if your baby is 3 months old or younger. They shouldn’t be used if your child has too much earwax or if they have an earache.
  • Temporal artery thermometer. Forehead thermometers are also used to measure your temporal temperature, but may not be as reliable as digital thermometers, and are usually more expensive. They’re placed on the temporal artery of the forehead and measure the infrared heat that comes off the head.

Some thermometers aren’t recommended due to their inaccuracy:

  • Plastic strip thermometers only measure skin temperature.
  • Pacifier thermometers aren’t precise and are difficult to use correctly because they have to stay in your child’s mouth for long enough to record a temperature.
  • Smartphone app thermometers.
  • Mercury glass thermometers.

“The main reason mercury glass thermometers aren’t recommended is that mercury can poison you,” explains Dr. Sullivan. “This can happen when the glass breaks and mercury is released. If you do still have one of these thermometers, you should contact your local waste department and find out how to dispose of hazardous waste properly.”

How to take a temperature

Want to make sure you’re taking a temperature the right way? Dr. Sullivan recommends the following:

Wash your hands and prep the thermometer

Before you use a thermometer, you want to make sure you wash your hands with soap and warm water.

If you’re using a digital oral thermometer, make sure it’s been cleaned in cold water or by using rubbing alcohol, then rinsed in cold water. A digital rectal thermometer should be cleaned in soap and warm water.

Place the thermometer

When using a digital oral thermometer, you want to place it under the tongue. Keep your mouth closed and keep the thermometer in place for about 40 seconds. Usually, the thermometer will make a beeping noise when the final reading is done. If you’re keeping track, record the temperature and the time.

“Do not eat or drink anything for at least five minutes before you take your temperature because the temperature of the food or beverage could make the reading inaccurate,” notes Dr. Sullivan.

If using a digital rectal thermometer, put a small amount of lubricant (petroleum jelly or Vaseline®) on the sensor (tip) of the thermometer. Then, place your child belly down on your lap or table, with one palm on their back. Or place them face-up, with legs bent toward their chest, and hold the back of their thighs with one hand.

Using your other hand, gently insert the thermometer into their anus until the tip is completely inside their rectum. Don’t force it if you feel resistance. Keep the thermometer steady with your hand until you hear the beep (around 30 seconds). Gently remove the thermometer and record the temperature and time.


Make sure you put a diaper or cloth under your child, as they may poop immediately after removal of the thermometer.

You can also use a digital thermometer to take an axillary temperature. For this method, the thermometer is placed in the armpit of young children or adults whose temperature can’t safely be done orally. This method isn’t as accurate as oral or rectal, but can be used as a quick first check. You can follow this with an oral or rectal reading.

Clean the thermometer

Once done taking a temperature, you need to clean your thermometer again.

Rinse your digital oral thermometer in cold water, clean it with alcohol and rinse again. For a digital rectal thermometer, clean the thermometer thoroughly with soap and water. You may want to clean it again with alcohol and then rinse it again.

When to call a doctor

If you have questions about how to take a temperature, call your healthcare provider. They can give you tips on what’s the best type of thermometer for your family and the best way to do a temperature check.

This is also a good time to ask things like how often you should recheck temperatures or if you should do anything to try to reduce the fever.

Call your healthcare provider right away if anyone in your household has a fever and any of the following:

  • Severe headache.
  • Stiff neck.
  • Swelling of the throat.
  • Confusion.
  • Any change that worries you.

Remember, you and your healthcare provider work together to keep you and your family members healthy. They’ll be glad to answer questions about what thermometers are best, how they should be used and which numbers are important to keep track of.

“While a fever may be scary, it’s also trying to tell you something,” affirms Dr. Sullivan. “Your provider is your partner in knowing what is being said and how to respond.”

Related Articles

Applying aloe vera to irritated skin
February 27, 2024
Do Home Remedies for Ringworm Actually Work?

Some natural home remedies may offer relief, but they lack scientific evidence and won’t typically cure the condition

Variety of medication pills and tablets and liquids
February 22, 2024
Is It OK To Take Expired Medicine?

Some types of expired meds may not be harmful, but they probably aren’t worth the risk

Shoe storage shelf home, including purses and bike helmets
February 14, 2024
Wearing Shoes in the House: ‘OK’ or ‘No Way’?

Leaving footwear on invites germs, bacteria, toxins and other unwanted guests into your home

Male consults with pharmacist about herbal supplement
February 13, 2024
Herbal Supplements: Why To Check With a Healthcare Provider First

Besides questionable effectiveness, herbal supplements aren’t safe for everyone

Teacup of tea and plate of toast
February 2, 2024
What To Eat, Drink and Avoid When You Have the Stomach Flu

Start slowly with clear fluids, and then move to bland, easy-to-digest foods

Male with eyes closed sitting hunched over, pinching area between their eyes
January 29, 2024
Headache and Fatigue: 11 Possible Causes That Can Trigger Both

Many factors, like dehydration, a cold or even your medication, can result in these common symptoms

various New Year's resolutions written in date planner, with weights and chocolate in foreground
December 28, 2023
8 Common New Year’s Resolutions and How To Keep Them

Whether you’re trying to work out more, drink less or manage stress, we can help set you up for success

patient lying on imaging table about to enter machine
December 14, 2023
CT Scan vs. MRI: How They Work and What They Show

CTs and MRIs use different technologies to show different things — neither is necessarily ’better’ than the other

Trending Topics

White bowls full of pumpkin seeds, dark chocolate and various kinds of nuts
25 Magnesium-Rich Foods You Should Be Eating

A healthy diet can easily meet your body’s important demands for magnesium

Woman feeling for heart rate in neck on run outside, smartwatch and earbuds
Heart Rate Zones Explained

A super high heart rate means you’re burning more than fat

Spoonful of farro salad with tomato
What To Eat If You’ve Been Diagnosed With Prediabetes

Type 2 diabetes isn’t inevitable with these dietary changes