The Facts About Fevers: It's More Complicated Than 98.6 Degrees

by Dr. Tanya Altmann

Since fever is often one of the first symptoms of COVID-19 for those who exhibit symptoms, taking our temperatures regularly has become more commonplace. However, some people might panic if their thermometer beeps and reads 0.2 degrees higher than 98.6 degrees Fahrenheit (37 degrees Celsius). The truth is, temperature checking is not as straightforward as it seems, but the more we understand how our body temperature works, the more confident we will feel about our thermometer readings. Let's look at common misconceptions and break down the facts about temperature taking and thermometers:

  1. Myth: Any temperature reading over 98.6 degrees indicates a problem.

    The Facts: You probably grew up believing normal body temperature was 98.6 degrees, and anything different meant you were sick. However, normal body temperature is a range, not one specific value, and that range varies from person to person. Learning your baseline body temperature, which you can do by checking your temperature twice a day every day for a week, is the best way to become aware of when there might be a problem. Your temperature will vary by a few degrees depending on many individual factors including your lifestyle, age and the place on the body where the temperature is taken. It's important to get to know your personal range so you can monitor when you are tracking high or low and what that may mean for you.
  2. Myth: You should take your temperature only when you feel sick.

    The Facts: We should be taking our temperatures daily. Once you know your baseline temperature range, you can be confident in knowing when something is amiss. It is helpful to share with your Doctor both what your temperature is right now as well as your baseline range when healthy.
  3. Myth: Mornings are the best time to take your temperature.

    The Facts: While the time of day you take your temperature affects your temperature reading, it's important to take your temperature twice a day, once in the morning and once late in the day. Some people running a fever might not register a high number in the morning but will by the afternoon, and that's because people run cooler in the morning, with their temperatures usually peaking between 4 and 9 p.m. If you are taking your temperature twice a day, at least one of the readings should be done during that evening window, and ideally around the same time every day, to account for any daily fluctuation.
  4. Myth: You need to take your temperature more than once in a row to get an accurate measurement.

    The Facts: You don't need to take your temperature more than once, as long as you read and follow the device directions. It's also important that you understand the various factors that might impact your reading, such as the time of day and any physical activity. If you know your baseline temperature, you are more likely to catch when a reading is off and as a result may watch for other illness symptoms and may even seek advice from your healthcare professional.
  5. Myth: If your child feels warm, it must be a fever.

    The Facts: Children can feel warm for many reasons. Children give off heat when they are playing, crying, getting out of a warm bed, or even because of hot weather. Their skin temperature should return to normal in about 20 minutes where you can then take their temperature and compare it against their normal body temperature. What you should look at is how your child is acting and any potential illness symptoms they have.
  6. Myth: Temperature values always read the same, no matter the location in the body where the temperature was taken.

    The Facts: The site of temperature measurement is important when understanding your temperature reading, as various sites in your body will give you different readings. For example, temperatures taken orally will usually yield a number about 1 degree lower than when taken rectally. If taken under arm, the temperature will be about half a degree to a degree lower than oral. Other more common sites of temperature measurement as a result of no-contact thermometers, such as the forehead, are more susceptible to ambient temperature and factors such as your clothing, so it's important to consider the temperature of the environment you've been in and any clothing such as hats that might affect your surface temperature in these sites. The ear, however, is an excellent site for measurement, as the ear accurately reflects the core body temperature because the eardrum shares the blood supply with the temperature control center in the brain. When core body temperature rises, it's quickly detectable in the ear. A thermometer such as Braun's ThermoScan 7 Ear Thermometer is a great choice if you want to take all of the guesswork out, because it also uses patented Age Precision technology for age-appropriate fever guidance, with a patented pre-warmed tip minimizing the cooling effect of the ear canal, so your measurements will be accurate time after time.
  7. Myth: Fevers are dangerous, especially for children.

    The Facts: A fever is your body's way of letting you know it is working hard to fight off an infection and its attempt to keep you from getting sicker. In today's climate, a fever in adults or older kids may certainly be worth a call to the doctor, and a good reason to stay home from school or work. Assess other symptoms and how the person is acting. It's also important to note that for babies under 3 months old, any temperature reading of 100.4 degrees or higher rectally, or 99.5 degrees from Braun's ear thermometer (Braun's oral equivalent reading), can often be concerning, so call your doctor immediately.
  8. Myth: Non-contact and skin temperature readings usually held near the forehead aren't quite as accurate because the readings can be affected by different factors such as sweat, makeup, the time of day and surrounding temperatures.

    The Facts: This is both true and false. Thermometer readings from a non-contact thermometer, such as a forehead thermometer, can be skewed by external factors that impact your surface temperature (i.e., clothing, physical activity), versus readings from other accessible parts, such as oral, rectal or ear. To ensure for a more accurate reading with a non-contact forehead thermometer, wait 15-20 minutes to ensure that the surface temperature has acclimated to the room temperature and avoid heating or cooling to the forehead with any external sources. External sources include wearing a hat or even sleeping face down in a pillow. Keep in mind that there are correct usage guidelines for any measurement site, and those using a thermometer should familiarize themselves with the tips for accurate measurement based on thermometer type.
  9. Myth: The most accurate thermometers are oral ones, which should be used at home.

    The Facts: The ear is one of the best sites for temperature measurement because it reflects the core temperature of the body, allowing for the most precise reading compared with other thermometers. Body temperature is regulated by the hypothalamus, which shares the same blood supply as the tympanic membrane. This means changes in core body temperature are usually detected sooner in the tympanic membrane than other areas. Unlike an ear thermometer, oral readings are more likely to be skewed by external factors other than true body temp readings, such as eating, drinking, smoking or even talking in a fast-paced manner.
  10. Myth: Ear thermometers are at greater risk of user error-and wax or other blockages may affect their accuracy.

    The Facts: Ear thermometers are an excellent way to take someone's temperature. Just make sure you use a new probe cover with your device for every measurement. Lens filters are a critical part to the accuracy of a thermometer when used in the ear-this protects the sensor lens from any contamination that could affect the accuracy. If you don't use lens filters, ear wax can build up over time on the lens and obscure the reading. A clean lens with lens filter installed on Braun's ThermoScan 7 will accurately read the temperature in the ear canal.

Dr. Tanya Altmann