Do You Have the Flu, RSV, COVID, or the Common Cold?

Nov. 22, 2023 – Winter is almost here, and with it may come runny noses, coughing, and congestion. But how do you know if you have just a common cold or one of the three respiratory viruses that make up the “tripledemic” – RSV (respiratory syncytial virus), COVID-19, and influenza? 

Based on symptoms alone, it’s difficult to tell which illness you might have. But there are clues that can point you in the right direction: how severe your symptoms are, how long it took for symptoms to set in, what viruses are circulating in your community, and more. 

We asked experts to break it down for us. 

How Viruses Set Themselves Apart – or Don’t 

Nowadays, COVID – especially for people who have received the most recent vaccine – can manifest much like a common cold, so it’s important to keep at-home tests on hand.

“Being vaccinated does keep [these viruses] from striking the chest,” said Panagis Galiatsatos, MD, a pulmonary and critical care doctor at Johns Hopkins. “Vaccinated patients may get a mild cough, but a lot of their symptoms stay more as an upper respiratory issue, like nasal congestion – like a bad cold.” 

RSV in healthy people who are not children or over the age of 65 might look like a cold or a mild case of COVID. But for children and seniors, a telltale sign of a potential RSV infection is when a patient is wheezing or they are having asthma flares, said Peter Chin-Hong, MD, an infectious disease expert at the University of California, San Francisco. 

What the Timing of Symptoms Can Tell Us 

Common cold symptoms tend to come on fairly quickly, explained Chin-Hong. If you get RSV, on the other hand, it may take 4 to 6 days before symptoms show. Flu viruses are a totally different story. 

“The special characteristic of flus is the abrupt onset of symptoms,” Chin-Hong said. “You might be minding your own business, feeling OK, and then all of the sudden you get in your car and you feel like you’ve been hit by a dump truck.” 

COVID also has some unique symptomatic features. You may not have symptoms at all, or you might have mild, cold-like symptoms for a week before the symptoms worsen and the infection becomes more serious. 

“COVID has this biphasic pattern, whereas colds and RSV don’t – it’s when you are kind of doing OK, and then you fall off a cliff,” said Chin-Hong. “That’s why early treatment with Paxlovid or remdesivir is so important because it can prevent that second phase from happening.” 

Testing Is Your Best Bet

For Galiatsatos, getting tested for COVID should be your first instinct – and getting two negative tests within a 24-hour period should encourage you to seek out a flu test at a local health care facility if you’re able to. Staying on top of testing can get you access to the right antivirals, like Tamiflu, which can shorten symptoms by a day or more. And when you come down with the flu, those couple of days can make a world of difference. 

Just assuming you have COVID and not testing could be a mistake, especially if you end up having long-lasting respiratory symptoms of the virus. 

“One of the things that broke my heart was so many patients who have come into my clinic with symptoms of long COVID, but they never got tested. I can’t test their antibodies anymore because those antibodies could be from an older infection or vaccine,” said Galiatsatos. “It’s hard to get insurance companies to pay for long COVID tests if there wasn’t a positive COVID test to begin with.”