From Nurse Blake: What is your baseline temp and why does it matter?

What to know about body temperature

A “normal” body temperature can range anywhere from 95.5°F to 99.9°F, with the average being 98.0°F when measured under the tongue (orally). Did you know your body temperature changes throughout the day? If you check your temperature frequently, you'll likely find that your body temp is lowest at 6 am and at its highest between 4-6 pm, with a difference of up to 1°F. 

Body temperature will also vary person to person. For example, studies have found that those with lower BMIs (body mass index) and those who are older in age have lower body temps; women tend to run higher than men; and underlying conditions affect our body temperature in many ways. Ovulation will also affect body temperature, so you may notice lower temperatures in the two weeks prior to ovulation.

I’d like to emphasize a piece from above: those who are older often have lower baseline body temps. Additionally, developing a fever is impaired in older adults. This means that a serious infection could be brewing, all while your thermometer reads “No Fever” or “Mild Fever.” Seeking care sooner rather than later is advised in adults over 65 years of age or anytime you’re concerned with an illness.

Find your baseline

Knowing your personal baseline temp can be key to spotting an illness early. To calculate your baseline temp: 

  1. Check your temperature 2x/day, morning and evening, for 5 days.
  2. Add all 10 temperatures together.
  3. Divide your total by 10. 

Voila! You now have your baseline temperature. (Note: This is not a perfect science but a solid estimate. 🙂)

Remember don’t check for your baseline temperature…

  • Directly after eating/drinking something
  • Immediately after a shower/bath, workout, or coming in from outside
  • During an illness

Now that you have your baseline temperature, you can use it as a way to monitor for potential infections.  An increase of more than 2°F in your healthy, baseline temperature is a good indicator of an infection. 

How to translate this new info to your Kinsa app

At the end of the day, it’s important to remember that a number is simply a number. If you feel very sick, you’re very sick, even if the number on the thermometer doesn’t validate this fact for you. And vice versa: if you feel fine, but the temp on the thermometer is reading “High,” don’t panic. How you feel (or how your child feels and looks) will always be more important than the number you see on your thermometer.

As much as I (Nurse Blake) wish I could adjust your temperature reading to account for your baseline temperature every single time, our thermometers aren’t quite there yet.  But we’ll keep trying!

Let me walk you through a hypothetical scenario. Say I’ve calculated my baseline temperature and it is 97.1°F. A few weeks later, I start feeling under the weather - I’ve got a headache and my Kinsa thermometer gives me a temperature reading of 99.5°F.

Since I have inside info on the Kinsa app (😉), I can tell you that 99.5°F will register as “No Fever.” However, now I am equipped with the knowledge that this is 2.4 degrees above my baseline temp PLUS, I’m not feeling very well. I have two options:

  1. Do nothing and see how I feel as time goes on.
  2. Hit the blue plus (+) sign in the bottom right-hand corner of the Kinsa app and add a temperature manually: after hitting the plus sign, click “temperature,” ensure I’m on the correct temp-taking route (oral) and that I’m on the correct family member’s profile (myself), click on “enter manual temperature” at the bottom of the screen, and slide the bar until it changes from “No Fever” to “Mild Fever.”

For legal reasons, I really want to emphasize that we are guessing what the fever is at this point and I only suggest this to you so your Kinsa app guidance can match up more closely with your baseline temperature. In this hypothetical scenario, I’ll now see a guidance recommendation for a Headache with a Mild Fever, as opposed to a Headache with No Fever. Sometimes the guidance will differ but other times it will be identical, depending on which symptoms you’ve entered.

Again, in general, the number is just a number. 99.5°F makes no clinical difference from 100.0°F. Knowing your baseline temp and knowing if you’re about 2+ degrees higher is most useful. With more knowledge you can focus on eating a healthy diet, increasing your water intake, and getting more sleep - maybe you can fight off a more serious bug if you see it creeping in early. Even if you can’t fight it off early, you can protect others by being more diligent with handwashing, mask-wearing, and avoiding vulnerable family members once you see this increase in your baseline temperature. Knowledge truly is power!