Temperature check: Tips for tracking a key symptom of coronavirus contagion

Reviewed by James Ives, M.Psych. (Editor)Apr 1 2020

After I was told I'd been exposed to the novel coronavirus, I tried to follow the best medical advice. I started working from home. I socially isolated. And I "self-monitored" for signs I'd been infected.

Or, at least, I tried to.

COVID-19 symptoms seem pretty clear. The dry cough and difficulty breathing. Fatigue. And the fever.

To track all that, the federal Centers for Disease Control and Prevention recommends that people who may have been exposed take their temperature twice daily. As someone who covers the outbreak, I understand the soundness of this advice. There's a nationwide shortage of coronavirus diagnostics, so health care providers are trying to reserve tests for people who have been exposed, are symptomatic or are at clear risk of dangerous complications.

What the CDC's guidelines don't note: Taking your temperature is surprisingly difficult.

Especially when, like most of my 20-something friends, you don't own a thermometer. (I do have a candy thermometer, but those aren't useful here. A meat thermometer wouldn't be, either.) I called my local CVS. They were sold out. Another friend told me he had checked four stores in our neighborhood and come up empty-handed. My twin brother was able to find one — but he lives in Connecticut, almost 400 miles from me.

When I checked online, I discovered I'd have to wait weeks to months for a thermometer, unless I was willing to shell out at least $50. I was not.

Since I had no symptoms - I still felt comfortable going out for a run or doing yoga in my kitchen — I decided to wait and watch. It's been two weeks, officially, and my only symptoms are cabin fever and existential anxiety. The coronavirus seemed a no-show.

But was that the best course of action? And what should people in my situation do?

I did what any health journalist would do. I researched and called the experts.

Their advice was comforting. Splurging on a pricey thermometer isn't the right move, especially if you aren't showing symptoms. There are other ways to figure out if you have a fever, or are at risk of COVID-19 complications. And a few principles are worth considering.

The number varies

First of all, for people like my brother, who was able to find a thermometer in stock and buy it, or those who actually owned one long before this need arose, the number you're looking for varies.

We're taught the average human temperature is 98.6 degrees Fahrenheit. But that isn't necessarily correct. Research published this year suggests the average human body temperature is a bit lower - maybe 97.9. It differs from person to person, based on factors like body weight, height, the weather, age or gender.

"Some people are like, 'Oh, I run a low temperature.' 'Oh, I run high.' That's right! There is variation," said Dr. William Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University.

Generally, keep an eye out for a temperature of 100.5 F or higher. But the timing matters, too. Some people running a fever might not register a high number in the morning but will by afternoon. That's because people run cooler in the morning, and their temperature peaks in the evening, usually from 4 to 9 p.m., he told me.

If you are taking your temperature twice a day, at least one of those should be done during that evening window — and ideally around the same time every day, to account for daily fluctuation.

Another factor to consider when using oral thermometers, advised Dr. Leigh Vinocur, a Maryland-based physician and spokesperson for the American College of Emergency Physicians: If you've just had hot coffee, or water or ice cream, wait a little bit before checking for fever.

The equipment?

That gets at another question. Are specific kinds of thermometers better than others?

If you can't find a thermometer, everyone told me - again, don't worry. (There are lots of other things to worry about!) But if you have options, you don't need anything fancy.

High-tech models, like the smart thermometer Kinsa, track and map where people register fevers. This has been touted as a way to help predict the spread of disease. But they're expensive. When in stock, they retail for between $35 and $69, per the manufacturer's website.

There are other digital scanning thermometers that use infrared technology to scan someone's forehead — from a distance! - and deliver an accurate temperature reading.

These are the kinds used in high-traffic settings like the airport, or before journalists can enter White House press briefings — scenarios in which you don't want to stick the same thermometer in multiple people's mouths, spreading germs. When in stock (and again, many are not), those can cost $60-$80. That doesn't include shipping, if you're ordering online.

But those high-end devices aren't necessary, especially at home.

"You don't have to have the most expensive one. You can get a cheap one," urged Dr. Brad Uren, an assistant professor and emergency doctor at the University of Michigan. Simple, under-the-tongue thermometers that (normally) retail for less than $10 are more than sufficient.

Actually, scanning devices can be more vulnerable to user error, said Dr. Rob Davidson, an emergency physician in western Michigan. He has seen them misread temperatures as lower than what's accurate.

In fact, when I was still trying to buy a thermometer, one friend warned me she has seen those lower readings occur at home — a reason she refuses to buy scanning devices now. (She also doesn't currently have a thermometer.)

Products marketed for children are fine for adults. The only real precaution, doctors told me, is to make sure you properly clean it between uses and among people - soapy water or sterilizing alcohol will usually do the trick.

Mom had the right idea

But for people like my friends, these are moot points. If we don't have thermometers and aren't ready to drop $50 on one, what else can we do?

Don't sweat the number. A specific temperature is only one of many indications of a fever. People will also have alternating chills and sweats, and body aches. And doctors don't consider the precise number when deciding whether someone is ill.

"Fever is a yes-no thing, and chills are a big thing," Davidson told me.

The childhood forehead test may be less precise than a digital reading, but it's generally accurate in gauging sickness, he added. No wonder my mom relied on it to determine if her kids were well enough to go to school.

Since talking to Davidson, my social isolation partner and I have designated each other as sole "forehead testers" for the duration of this period: an effective way to self-monitor and mitigate germ-spreading from either of us to the rest of the world.

And if you are sick and seem to be registering a high body temperature? Call the doctor. If you're really worried (or if, like me, you don't have a primary care doctor), you may have to call the ER instead.

That said, the severe shortage of coronavirus tests and medical supplies — a shortage many worry will soon include hospital beds themselves - means running a temperature or having a fever won't get you into the hospital, even if you might have the coronavirus. It probably won't even qualify you for diagnostic testing.

To register that level of concern, doctors said, you need to experience trouble breathing so bad that you feel winded walking to the mailbox or even to the refrigerator.

If that doesn't happen, care for yourself at home. Self-isolate. Rest. Drink plenty of fluids, and take acetaminophen. (And my grain-of-salt advice: I swear by the healing powers — or at least comfort capacity - of Cocoa Puffs and Ritz crackers.)

Otherwise, follow basic infection-control guidelines (which don't necessarily involve rushing out to the drugstore as soon as a new stock of thermometers is delivered): Wash your hands frequently with soap. Avoid touching your face. Put on your favorite isolation playlist, or some early-season "Gilmore Girls," and practice your social distancing.