Whether you’re dealing with a sudden wave of chills and aches and pains, or you just feel *a little* hotter than usual, the desire to know if you have a fever ASAP is understandable. After all, a fever tends to serve as an indicator that your body is fending something off (like a virus or a bacterial infection). And, of course, we’re now in a cold and flu season that’s also happening during a global pandemic. You shouldn’t panic if you feel feverish, but it's *a lot*.

If you don’t have a thermometer laying around, or the only one you could find was buried deep in some bathroom drawer and you’re not sure just how long it’s been in there, is there any legit (or at least somewhat legit) way to gauge whether your temperature is above normal without a thermometer?

Read on to learn what to do if you’re feeling feverish, no matter your thermometer situation, with insight from immunology specialists.

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First thing’s first: Do you *need* a thermometer to tell if you have a fever?

The only way to know for sure that you have a fever is by taking your temperature with a thermometer, confirms David Erstein, MD, an allergist and immunologist based in New York. Doctors usually don’t consider you to have an ~actual~ clinically diagnosable fever unless it’s 100.4 degrees Fahrenheit or above.

Also, asking for a friend here: Can you have a fever without a temperature? This is actually a super common question (you—er, your friend—are not alone!), but experts agree that the answer is no. “You cannot have a fever without having a temperature,” says Jehan Riar, MD, a board-certified primary care physician with Mercy Personal Physicians. “Your body temperature being higher than normal is what a fever is.” Most people are in the general range of 98.6 for a normal temperature, but everyone is slightly different, Dr. Riar says.

Unfortunately, your chances of accurately guessing whether or not you have a fever without a thermometer are fair at best, she says. Case in point: Patients who self-reported feeling feverish at a rural teaching hospital in India had a 58 percent chance of *actually* having a fever, according to a study in Tropical Medicine and International Health.

If you’ve managed to dig up an old thermometer, digital and old-school glass thermometers alike should do the trick (as long as they’re not damaged or out of juice), says Robert Eitches, MD, an allergist-immunologist and fellow of the American Board of Allergy, Asthma, and Immunology. But if there’s any indication that your old-school thermometer is cracked or broken, wrap it up in a Ziploc bag and throw it away. Mercury (a silvery white liquid still present in some household thermometers) could leak out, and it’s toxic.

Of course, before you pop a thermometer under your tongue, you’ll want to clean it. Here's how to clean a thermometer properly:

  1. Lather up some soap and water in your hands, scrub down the part of the thermometer you put in your mouth for 20 seconds, and rinse it off.
  2. If you have rubbing alcohol on hand, wipe down the thermometer applicator with a cotton ball soaked with rubbing alcohol to sanitize it.
  3. Rinse it off again to remove the alcohol, advises Dr. Erstein.

If you don’t have any rubbing alcohol at home, no worries—washing it off with soap and water is absolutely fine (as soap alone can break down and remove bacteria and viruses, including the novel coronavirus), he says.

What if you don't have a thermometer on you? Are there any other ways to tell if you're feverish?

If you don’t have immediate access to a thermometer but you’re feeling, well, warm and icky, there are a few ways you can make an educated guess as to whether or not you actually have a fever.

Both digital and old-school glass thermometers are fine to use to measure fever.
  1. Listen to your body. Chances are, you’re already well-acquainted with what a fever feels like for you, from burning up so much so you have to throw off your sheets and turn up the A/C to out-of-the-ordinary shaking chills, tiredness that goes beyond the typical end-of-day fatigue, or headaches, body aches, and pains that can’t be explained. If any of the above sounds familiar, you might have a fever, notes Dr. Erstein.
  2. Take a look in the mirror. When you’re really burning up from a fever, you may appear flushed, red in the face, and sweaty, says Dr. Erstein.
  3. Get moving. Working out with a cold is the worst, and you shouldn't try this if you feel really run down. But if you’re up for some gentle movement, go on a brisk walk, jog up and down the stairs at your house, or try to lift a few weights. If you feel easily tired, weak, or winded, that could be another indicator that your body is battling an invader and your temperature’s up as a result, says Dr. Erstein.
  4. Have someone else feel your forehead. While it’s tough to gauge your own temperature with the ol’ back-of-hand-to-forehead trick (because if you are feverish, your entire body feels hot anyway), it can be helpful if you have a family member, roommate, or friend lend a hand. “If someone else feels your forehead and it feels hot, you most likely have a fever,” says Dr. Erstein.

Again, though, the only way to be totally sure your temperature’s off the charts is to use a thermometer.

How long does a fever last?

This falls squarely into the “it depends” category. “It depends entirely on what’s causing the fever,” says Aline M. Holmes, DNP, RN, a clinical associate professor at Rutgers University School of Nursing. If you have an isolated health issue, like a cold or strep throat, the fever could go on for a few days. “If you get started on an antibiotic with something like strep throat, the fever will come down quickly—often in less than 24 hours,” Holmes says.

If you have an active infection going on in your body, “you could have the fever as long as you have the infection,” Dr. Riar says. “It really depends on what the cause of the fever is,” she adds.

When should you seek medical attention for a fever?

If you feel ill and you’ve got a moderately high fever (think: above 102 degrees Fahrenheit or 38.9 degrees Celsius), that’s your cue to call a doctor to figure out next steps, says Dr. Eitches. Otherwise? “In general, if you’re experiencing fever associated with other symptoms such as shortness of breath, a rash, or confusion, it’s probably best to seek medical attention,” he says.

How do you treat a fever?

Again, it depends on what’s behind your fever, but there are a few interventions you can try. “If it’s a viral infection, you kind of have to ride it out,” Dr. Riar says. “It will eventually resolve with rest.”

Taking a pain reliever and fever reducer like acetaminophen (Tylenol) can help you feel better and may also help your fever to break, she says. You can also try taking a cool shower for relief, Holmes says.

Just know this, per Holmes: “If you’re not bothered by your fever and you’re feeling okay, you really don’t need to treat it.”

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Lauren Krouse
Lauren Krouse is a freelance writer who covers health, domestic violence, and self-advocacy. Her work appears in _Women’s Health, Men’s Health, Prevention, Self, HuffPost, and elsewhere. When she’s not writing, you can find her trying to meditate more, weightlifting, or walking in the woods with her partner and black lab.