Thermometers: Understand the options

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Thermometers: Understand the options

Thermometers come in a variety of styles. Understand the different types of thermometers and how to pick the right thermometer for you.

By Mayo Clinic staff

Choosing the thermometer that's best for your family can be confusing. Here's what you need to know about the most common thermometers.

Digital thermometers

Regular digital thermometers, which use electronic heat sensors to record body temperature, can be used in the rectum, mouth or armpit. The most accurate way to take a child's temperature is to use a digital thermometer, either rectally or orally. Rectal temperatures provide the best readings for infants, especially those 3 months or younger as well as children up to age 3. If you use another type of thermometer to take a young child's temperature and you're in doubt about the results, take a rectal temperature. For older children and adults, oral readings are usually accurate — as long as the mouth is closed while the thermometer is in place. Armpit readings tend to be less accurate than rectal and oral readings.

• Pros. Most digital thermometers can record temperatures from the mouth, armpit or rectum — often in a minute or less. A digital thermometer is appropriate for newborns, infants, children and adults.
• Cons. Parents may worry about causing discomfort when taking a child's temperature rectally. Wait at least 30 minutes after eating or drinking to take an oral temperature. Having nasal congestion may make it difficult to keep your mouth closed long enough to get an accurate oral reading from a digital thermometer. If you plan to use a digital thermometer to take both oral and rectal temperatures, you'll need to get two digital thermometers and label one for oral use and one for rectal use. Don't use the same thermometer in both places.

Digital ear thermometers

Digital ear thermometers, also called tympanic thermometers, use an infrared ray to measure the temperature inside the ear canal.

• Pros. When positioned properly, digital ear thermometers are quick and fairly accurate. Digital ear thermometers are appropriate for infants older than age 6 months, older children and adults.
• Cons. Digital ear thermometers aren't recommended for newborns. Earwax or a small, curved ear canal also can interfere with the accuracy of a temperature taken with a digital ear thermometer.

Digital pacifier thermometers

If your child uses a pacifier, you may want to try a digital pacifier thermometer. Your child simply sucks on the pacifier until the peak temperature is recorded.

• Pros. Your child may not even realize you're taking his or her temperature.
• Cons. Digital pacifier thermometers aren't recommended for newborns. For the most accurate reading, your child must hold the pacifier still in his or her mouth for about three to five minutes — which is difficult for many young children, particularly those who have nasal congestion. Recent research doesn't support the accuracy of temperature readings from pacifier thermometers.

Temporal artery thermometers

Temporal artery thermometers use an infrared scanner to measure the temperature of the temporal artery in the forehead.

• Pros. Temporal artery thermometers can record a person's temperature quickly and are easily tolerated. Temporal artery thermometers are appropriate for infants older than age 3 months and older children. New research suggests that a temporal artery thermometer also might provide accurate readings for a newborn.
• Cons. A temporal artery thermometer may be more expensive than other types of thermometers.

Temperature strips

Temperature strips contain liquid crystals that react to heat. Simply apply a temperature strip to the forehead, and the strip will register body temperature by changing color.

• Pros. Temperature strips are easy to use.
• Cons. Temperature strips aren't precise. The temperature of a person's surroundings can affect the recorded temperature. If you need an exact temperature reading, use a digital thermometer instead.

Mercury thermometers

Once a staple in most medicine cabinets, mercury thermometers use mercury encased in glass to measure body temperature. Mercury thermometers can record temperatures from the mouth, armpit or rectum — but they're no longer recommended because they can break and allow mercury to vaporize and be inhaled. If you have a mercury thermometer, consider replacing it. But don't throw a mercury thermometer in the trash. Contact your local trash collection program to see if there's a hazardous waste site in your area.

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