Is it a cold, the flu or COVID-19? How to tell the difference

Cold is easier to distinguish from flu and COVID-19, but symptoms of COVID-19 and the flu are very similar.
/ Source: TODAY

The coronavirus epidemic has changed pretty much everything about life as we knew it, and the upcoming flu season is no exception. With COVID-19 still spreading in much of the country, wearing a mask and social distancing are as important as ever.

In fact, these precautions could also reduce the spread of flu and colds over the next few months, Dr. Walt Orenstein, professor of infectious diseases at Emory University School of Medicine in Atlanta, told TODAY. In addition to following coronavirus guidelines this winter, it's also important to understand the subtle differences between the symptoms associated with cold, flu and COVID-19. Here's a guide.

How is the flu related to COVID-19?

Influenza and COVID-19 are both contagious, respiratory illnesses, but they come from different viruses, according to the Centers for Disease Control and Prevention. The virus that causes COVID-19 is called SARS-CoV-2, and the flu is caused by influenza viruses.

The coronavirus and influenza viruses lead to similar symptoms, so they can be difficult to distinguish from each other, Dr. Eric Cioe-Pena, emergency medicine physician at Northwell Health in New York City, told TODAY.

Thinking about how you were exposed could help you determine if you have COVID-19 or flu. For example, if you had "an interpersonal, higher-risk exposure (to someone who may be COVID-19 positive), I would more strongly suspect COVID," Cioe-Pena said.

Similarities and differences between flu and COVID-19 symptoms

According to the CDC, these symptoms frequently occur in both flu and COVID-19:

  • Fever (above 100), chills or feeling feverish
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue
  • Sore throat
  • Runny or stuffy nose
  • Muscle pain or body aches
  • Headache
  • Gastrointestinal symptoms

The only symptom that occurs almost exclusively in COVID-19 is loss of (or changes) to your taste and smell. "That is generally not seen with influenza, and if that happens, that really suggests you have COVID," Orenstein explained.

That said, not everyone who contracts the coronavirus loses their taste or smell, so this isn't a foolproof distinction. If you have any of the above symptoms and your taste and smell remain intact, it still could be COVID-19.

Similarly, sneezing is most common with colds, less common with flu and least associated with COVID-19. But the presence of sneezing doesn't rule out COVID-19, Cioe-Pena said, adding, "nothing about this virus is absolute."

A recent study suggests you might want to track the progression of your symptoms to distinguish flu and COVID-19: It found that fever was most likely to be the first symptom experienced by people with COVID-19; while a cough was most likely to be a first symptom of the flu. And though it may be rare, it is possible to contract COVID-19 and flu at the same time.

How long does it take to show flu symptoms versus COVID-19?

With both COVID-19 and flu, symptoms can develop as fast as one to two days after exposure, according to the CDC. That said, people with COVID-19 usually take longer to develop symptoms.

With the coronavirus, a person typically develops symptoms five days after infection, but it can take anywhere between two days and two weeks. With the flu, symptoms usually appear one to four days after infection.

What are the differences between allergies, cold and COVID-19?

Cold will generally be easier to distinguish from flu and COVID-19 than they are to distinguish from each other, Dr. William Schaffner, medical director of the National Foundation for Infectious Diseases in Bethesda, Maryland, told TODAY.

Symptoms more common with colds and less common with flu or COVID-19, per Schaffner, include:

  • Symptoms that stay above the neck (for example, not a chest cough)
  • No fever or very low fever (below 100)
  • Sneezing
  • Nothing more severe than a stuffy nose or sore throat

Still, if you only have these mild symptoms, then it could still be COVID-19 or the flu, Schaffner said, adding, "All of them can overlap and masquerade."

On the other hand, if your symptoms are severe, it's less likely to be a cold, according to Cioe-Pena. If "someone (has a 104 fever), they're dehydrated and looking like they need IV fluids, it's usually either flu or COVID," he said.

Another way to assess if it's flu or COVID-19 versus a cold? Think about the level of flu and coronavirus in your community — and your habits, Schaffner said.

"Are you a mask-wearing, sheltering, 6-foot-distancing, avoiding-large-groups person? Or are you a person who goes out and about?" he said. "If you’re a careful person, it’s less likely you’ll have COVID or flu."

Wondering if it's allergies or COVID-19? This isn't the year to assume you're developing fall or winter allergies for the first time and act as though you're not contagious, Cioe-Pena advised. But if it's an annual occurrence, then there's no need to "go crazy" thinking you might have COVID-19 or the flu, he said. One thing to note is that itchiness is usually a "hallmark sign" of allergies.

Just make sure your symptoms stay consistent with previous years and are mild — for example, an itchy nose with clear runoff — and that you feel better after taking your typical allergy relief, like Claritin.

How can you protect yourself this flu season?

Orenstein, Schaffner and Cioe-Pena offered the following strategies:

  • Get a flu shot by the end of October. Tell everyone you know to do the same. (It won't protect against the coronavirus, but it's an important public health measure.)
  • Take precautions to prevent spread of the coronavirus, especially social distancing, regular hand washing, wearing a mask and interacting with people outside your household only outdoors.
  • Stay home if you have any signs of being sick. If you're on the fence about whether you can safely leave your house, contact your health care provider.
  • If you're young, healthy and only have mild illness, call your health care provider before visiting an office setting or hospital.

Last, if you know you've been exposed to COVID-19, contact your health care provider as soon as possible.