Is The Mercury Thermometer More Accurate Than The Digital Thermometer?

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Those who have children have to deal with fever, and taking their temperature is necessary. So, what kind of thermometer should you use? 

To get more information, I talked with a friend (a materials specialist, graduate from a key university, who holds a master degree): 

Friend: Of course, a mercury thermometer is more accurate. Hospitals use mercury ones.

Me: Why do you think the mercury thermometer is more accurate?

Friend: Don't you think the more processes involved, the more the interference will be? The conversion between heat and digital signals is undoubtedly not so accurate, which is especially true for cheap digital thermometers 

Me: Really? Is the mercury thermometer based thermal expansion more inaccurate? In particular, processing the glass tube is subject to uncertain factors. 

Friend: You're wrong. The processing is simpler than that of a thermistor: the simpler, the more reliable. As long as there is conversion, you will get a less accurate result.

The reasoning is so great that I don't know how to refute it for a moment. 


When used correctly, the digital thermometer is accurate enough to meet daily needs and safer than the mercury thermometer. More importantly, the temperature measurement is only a reference, whether to administer medicine to children or take them to the hospital depends on the judgment of symptoms and feelings. 

You don't think the digital thermometer is accurate because you used it wrongly.

At present, there are mainly three kinds of electronic temperature measuring instruments in the market: ear thermometer, forehead thermometer, and digital clinical thermometer. 

The ear thermometer and the forehead thermometer mainly rely on the sensor to receive the infrared rays from the human body to detect the body temperature. In an ideal condition, the results are accurate. Many people think it inaccurate mainly because they use the instruments in the wrong way. 

There are too many factors affecting the forehead temperature, including room temperature,  skin dryness, and more. The measurements you get after you wash face or use an ice bag can not reflect the right body temperature. 

No formal medical facility uses a forehead gun as a tool to judge whether someone has a fever or not. 

However, the forehead thermometer stands out because of convenience. They are often used in kindergartens, playgrounds, airports, railway stations where there are a lot of people for rapidly screening patients with fever. 


▲ The advantage of the forehead temperature gun is that it is convenient and fast.

The ear thermometer measures the temperature of the eardrum, which perfectly reflects the real body temperature. It is most medical organizations use ear thermometers to take the temperature in place of the mercury thermometer. 

There are different types of ear thermometers. Some need to put on a disposable "hat," some do not need it. If there is a mistake, or if the "hat" is damaged, the measurement won't be accurate. 

Moreover, because the ear canal is not straight, as for kids under the age of 3, it is necessary to lift the auricle outward. Only by doing so, can you put the ear thermometer in the correct position.

For babies under 6 months, their ear canal is smaller, so you shouldn't use an ear thermometer. 

Additionally, if repeatedly measuring in a short time, the ear thermometer itself will affect the temperature of the ear canal, as well as the accuracy of the measurement. 


▲ The ear thermometer is the right choice for family use  

The digital clinical thermometer features the most stable performance among the 3 kinds of electronic thermometers. 

The operation and notes are similar to the standard mercury thermometers which are put under the tongue, armpit or rectum. Most people can use them intuitively. The accuracy of the measurement is also very high. 

But the downside is that it takes a little longer to measure body temperature than the first two devices. It takes from 30 seconds to over 3 minutes to get the measurement for different brands.

Additionally, drinking (cold drink, hot drink), strenuous exercise, bathing, and so on affect the measurement results. You need to wait for at least 30 minutes. 


It takes a long time for a digital clinical thermometer to measure the temperature. Moreover, taking a squirming kid's temperature might be challenging.

3 electronic thermometers mentioned above have common shortcomings, i.e., they have strict requirements on the usage. That's why most people think that the mercury thermometer is more accurate.

To get accurate results, be sure to read the instructions carefully. The usage of products from different manufacturers may differ. Generally, the more expensive a thermometer is, the more accurate the measurement you can get. 

Some people might think of: I would use a mercury thermometer instead. After all, many hospitals use this kind of thermometers.  

The main reason why hospitals use mercury thermometers is low cost. 

They don't need to worry that mercury thermometers will be lost, stolen, or damaged. Moreover, it is easy to use for everyone. 

Another reason is that mercury thermometers are easy to clean and disinfect. In hospitals, a large number of patients use thermometers, and contact leads to risks of cross-infection. According to the requirements of disinfection and quarantine, a thermometer needs to be sterilized with 500 mg/L chlorine solution. Electronic products can't be disinfected in this way. 

Meanwhile, you can't ignore the shortcomings of mercury thermometers. Made of glass, they are easy to be broken, and the mercury will pollute the environment, which is bad for health. 

The World Health Organization advocates the elimination of mercury thermometers and mercury sphygmomanometer by 2020, which means that the great invention will step down from the stage. 

In place of mercury thermometers, hospitals will use the ear thermometer to take body temperature. The disposable "hat" of an ear thermometer can be replaced, and do not need to be soaked and disinfected. 

For daily use, despite prices, a digital thermometer is the best choice. 


▲ Using mercury thermometers is risky in families.

Body temperature serves as a reference - symptoms and feelings matter. 

In daily life, when my child has a fever, I choose to touch and use an ear thermometer. 

Use your hand to feel the temperature, and you can know whether it is hot or not. Then, use an ear thermometer to confirm. The accuracy and error of the measurement of an ear thermometer are always reasonable.

According to a well-received formula, the armpit temperature plus 0.5℃ equals mouth temperature. Mouth temperature plus 0.5℃ is the canal temperature. The formula is inaccurate. The temperatures of different body parts vary as the normal ranges are different. They are subject to various factors, such as ages, clothing, exercises, etc. Comparing temperatures of different parts for different people makes no sense.

Especially when you see a doctor, tell the doctor, "My ear temperature is 38.2℃." You don't need to add or subtract; otherwise, it may affect the doctor's judgment. 

Most importantly, the body temperature is just a reference. One should take medicines according to the symptoms and feelings.


In general, doctors advise you to take antipyretics when your temperature goes above 38.5℃,  which is temporary. You don't need to have medicines regularly. 

For example, acetaminophen is used every four hours (no more than 5 times within 24 hours). It does not mean that it needs to be reused every four hours after the fever is gone. 

You should also examine your baby's state before administering the medicine. If he/she eats well, and in a high spirit, medication is unnecessary.

And if the baby is shivering, with cold hands and feet, and he/she looks pale, the body temperature might be on the rise. You should keep his/her hands and feet warm and improve comfort. It is also feasible to administer medicines according to your experience. Don't have to wait till the temperature exceeds 38.5℃.

If the body temperature rises above 41℃, apart from antipyretic, you should also use physical treatment to quickly lower the body temperature and see a doctor as soon as possible. 

After having some medicines, a kid will sweat a lot. They must drink some water on time. 

Sweating is a way to dissipate heat when one has a fever. Be sure not to cover the body to sweat.

If the excess temperature (above 40℃) lasts for one day, or the temperature remains above 38.5℃ for three days, the patient suffers from vomiting, severe diarrhea, convulsions, tachypnea, mental depression, lethargy, coma, oliguria, or else, seek medical attention in time. 


If you don't know what excellent ear thermometers, forehead thermometers, and digital clinical thermometers are available, have a look at the recommended products below: 

Top ear thermometers:

1. COZZINE ET101H Infrared Ear Thermometer

- High accuracy: + / - 0.2 degrees Celsius, Fahrenheit + / - 0.4

- Quick detection: only takes 2 seconds to test the temperature

- Thoughtful fever warning: when the body temperature exceeds 37.8, it will display a "crying face" symbol and warn you with 3 short beeps and a final long beep

- Memory storage function: stores and recalls up to the latest 10 measurements

- Comes with earmuffs to avoid cross-infection


COZZINE ET101H Infrared Ear Thermometer

$9.03

$9.03


2. ACurio AT - 606 LCD Digital Baby Ear Infrared Thermometer

- Measurement range : 34 - 42.2 Deg.C 

- Fever warning: when the reading exceeds 37.5 Deg.C/99.5 Deg.F, it will warn you that may have a fever by 1 long and 3 short signals beep

- Memory storage function: stores and recalls 9 set of previous readings

- Deg.C and Deg.F switchable


ACurio AT - 606 LCD Digital Baby Ear Infrared Thermometer

$14.4

$13.1


Top forehead thermometers:  

1.Xiaomi Mijia iHealth Thermometer

- High accuracy: + / - 0.2 degrees Celsius, Fahrenheit + / - 0.4

- Quick detection: 1 second to get the reading

- Advanced German Heimann Sensor for accurate detection

- Non-contact infrared detection

- Concealed LED digital display

- Ease of use


Xiaomi Mijia iHealth Thermometer

$38.5

$32.75


2.Alfawise CK-T1803 Medical Digital Infrared Thermometer

- Quick detection: 1 second to get the reading

- Memory storage: stores 32 sets of data

- Non-contact infrared detection

- LCD screen with bright backlight

- Deg.C and Deg.F switchable

- Ideal for measuring body temperature, milk bottle, food, bath water, etc.


3.guucy FI01 Smart Baby Forehead Thermometer

- High accuracy

- Quick detection

- Color screen

- Ease of use

- Measuring range: 32 - 42.9 Deg.C (human body), 0 - 100 Deg.C (object)

guucy FI01 Smart Baby Forehead Thermometer

$20.77

$14.38


Top digital clinical thermometers:

1.Xiaomi MMC-W201 LCD Medical digital thermometer

- High accuracy: + / - 0.1 Deg.C (35 - 39 Deg.C ), + / - 0.2 Deg.C (32 - 34.9 Deg.C / 39 - 42 Deg.C )

- No Hg, no need to worry about glass breaking or mercury leaking problem

- Dual-purpose: oral and underarm temperature measurement

- 18.8mm LCD screen

- Advanced German Heimann Sensor for accurate detection


Xiaomi MMC - W201 LCD Medical Electronic Thermometer

$6.49

$6.49


2.Portable Digital Electronic Oral Thermometer

- Sensitive and high accuracy

- Dual-purpose: for mouth, rectum and oxter use

- Portable design

- Beep sound when completes measurement

Portable Digital Electronic Oral Thermometer

$2.49

$2.47


3.Digital Electronic Flexible Thermometer

- Sensitive and high accuracy

- Dual-purpose: for mouth, rectum and oxter use

- Portable design

- Beep sound when completes measurement


Portable Digital Electronic Flexible Thermometer

$2.99

$2.35


4.Gocomma T11 Portable Thermometer

- High accuracy: + / - 0.1 Deg.C

- Dual-purpose: for mouth, underarm and anus use

- Memory storage

- Measurement range: 32-42 Deg.C

Gocomma T11 Portable Thermometer

$5.99

$5.99


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