Doctor Reveals the COVID Symptoms That Show Up Before You Test Positive

There are a number of a respiratory viruses circulating this winter. You could get hit with the flu, RSV, or, yes, COVID—which is still spreading well after the official end of the pandemic. According to data from the Centers for Disease Control and Prevention (CDC), the JN.1 variant recently caused a spike in coronavirus cases throughout the U.S., but the agency says respiratory disease activity overall is elevated, making it hard to know whether your symptoms are a sign of COVID or something else.

It's especially challenging to tell the difference between COVID, the flu, and RSV without testing, because "COVID can most commonly present like most other upper respiratory tract infections at this point," Thomas Holland, MD, associate professor of infectious diseases at Duke University School of Medicine in North Carolina, told HuffPost.

Nevertheless, many people experience headache or fatigue as their first symptoms of COVID, according to Holland—and those signs can show up before you test positive for the virus.

"There's some evidence that people are more likely to test positive or more likely to reach their maximum viral shedding … a little bit later than earlier in the pandemic," Holland shared. "The counseling for years with COVID was that you were maximally infectious … right around the time that you develop symptoms, and that's probably pushed back a little bit later to a day or two or three days after onset of symptoms, probably because most of us have some immunity to COVID at this point, either from vaccination or viral infection, or both."

That doesn't mean you shouldn't test, however. It does mean that you may test negative when you first come down with a headache or fatigue, before testing positive a few days later.

"It's important to test," S. Wesley Long, MD, medical director of diagnostic microbiology at Houston Methodist Hospital, told HuffPost. "We have medications to treat flu, we have medications to treat COVID [and] they're different, one won't work on the other. And none of those medications will work for the common cold."

Of course, headache and fatigue are not likely to be your only COVID symptoms. And they're two signs that could be associated with "really any respiratory virus," according to Long. Wondering what other symptoms you should look out for as you wait to test positive? Read on for four other common signs.

RELATED: COVID Now Causing These Unusual Symptoms, New Data Shows.

Besides headache, David Strain, associate professor of cardiometabolic health at the University of Exeter, recently told BBC that JN.1 patients are often experiencing diarrhea as an early COVID symptom.

He's not the only medical professional to point this out.

"There is some suggestion that JN.1 may be causing more diarrhea than previous variants, but we don't have any firm data supporting that yet," Andy Pekosz, PhD, professor in Molecular Microbiology and Immunology, said in an interview for Johns Hopkins Bloomberg School of Public Health.

RELATED: JN.1 COVID Patients Are Presenting With 2 Specific Symptoms First, Doctors Say.

The U.K. Office for National Statistics (ONS) conducted a survey in early Dec. 2023 and found that 10.8 percent of respondents reported that they struggled to sleep when they had COVID. In response to the data, a spokesperson for the CDC previously confirmed to Best Life that the agency has been investigating this as well.

"There have been reports that COVID-19 may be associated with insomnia … in some patients, and therefore that can be a general symptom of infection," the spokesperson said.ae0fcc31ae342fd3a1346ebb1f342fcb

RELATED: Why the New COVID Variant Could Make You Sick Longer, Doctor Says.

Last fall, several doctors told NBC News that they were seeing sore throat as one of the first COVID symptoms. Some patients have described "a burning sensation like they never had, even with strep in the past," Grace McComsey, MD, vice dean for clinical and translational research at Case Western University, told the news outlet at the time.

After their sore throat clears up, many COVID patients are experiencing congestion, William Schaffner, MD, professor of infectious diseases at Vanderbilt University Medical Center, told Parade at the end of last year.

This nasal congestion typically comes alongside "a runny nose and feeling run down with fatigue and muscle aches," according to Schaffner.

Best Life offers the most up-to-date information from top experts, new research, and health agencies, but our content is not meant to be a substitute for professional guidance. When it comes to the medication you're taking or any other health questions you have, always consult your healthcare provider directly.