Not feeling well? With the COVID-19 pandemic ongoing — and the Omicron variant at large — a cough, headache, fever, upset stomach, or body ache can cause panic: Do I have COVID? Or is it the seasonal flu, a common cold, or just allergies?
Both influenza and COVID are contagious respiratory illnesses, which explains some of the similarities in symptoms. But they are caused by different viruses: The flu is caused by infection with an influenza virus, which can change and mutate annually; COVID is caused by infection with the SARS-CoV-2 coronavirus, which was first identified in 2019 but has also mutated into variants, states the Centers for Disease Control and Prevention (CDC).
Although the symptoms are similar, there are important ways to tell COVID apart from other illnesses. The best way to be sure is to get tested, of course, but below is advice from the nation’s top experts on how to suss out the difference between COVID and seasonal illnesses.
Step 1: Research what’s prevalent in your community.
As Peter Palese, PhD, microbiologist and flu expert at New York City’s Icahn School of Medicine at Mount Sinai, told the New York Times, if influenza is making the rounds and COVID cases are on the downswing, it could be more likely you have a flu. If COVID’s raging and the flu is not, you might have COVID. COVID appears to spread more easily than flu, states the CDC. And if a person has COVID, they can be contagious for a longer time than if they have a flu. Plus, with COVID, people can take longer to show symptoms.
Step 2: Learn which symptoms the flu and COVID share.
The Mayo Clinic reports that both can cause these symptoms:
- Fever or chills (although not all flus result in a fever)
- Shortness of breath or difficulty breathing
- Body aches
- Sore throat
- Congestion or runny nose
- Vomiting or diarrhea (this is more often a symptom with children, reports Lisa Lockerd Maragakis, MD, MPH, senior director of infection prevention at the Johns Hopkins Health System in Baltimore).
Step 3. Know which symptoms are specific to COVID.
While both can cause coughing, COVID usually results in a dry cough compared with the wet cough of the flu, notes the Mayo Clinic. Diarrhea, nausea, and vomiting are more common symptoms in adults with COVID and are only rarely a symptom in adults with the flu, reports the Mayo Clinic.
The key distinguishing symptom to look for with COVID, though, is a sudden loss of sense of smell (which is known as anosmia) or taste (ageusia) — although this does not always occur with COVID cases, Maragakis says.
The flu does not usually affect a person’s sense of smell or taste. Still, with certain rare strains of the influenza virus, as was the case during the 1918 flu pandemic, people may lose their sense of taste or smell, Maragakis states.
Step 4. Realize that you may instead have a cold, states the Mayo Clinic.
Like COVID, the common cold is caused by a virus, although in this case, it’s a rhinovirus. Still, it can cause many of the same symptoms, although there are some key differences:
- Coughing: Again, COVID typically results in a dry cough versus the wet cough of a cold.
- Muscle aches and fever: While these are common with COVID, they are only sometimes symptoms of a cold.
- Diarrhea, vomiting, or nausea: These almost never occur with a cold.
- Loss of taste or smell: This can sometimes happen with a cold, especially if you have a stuffy nose.
Step 5. Realize that you may instead have seasonal allergies, the Mayo Clinic notes.
COVID symptoms are quite different:
- Muscle aches and fever: These almost never occur with allergies.
- Diarrhea, vomiting, or nausea: These almost never occur with allergies.
For more on these differences, see the Mayo’s handy comparison tables.
Step 6. How can I know for sure?
It’s important to understand that people can have COVID and the flu, COVID and a cold, and/or COVID and seasonal allergies at the same time, the experts warn. Ultimately, testing is the best way to determine what the illness is and confirm a diagnosis, advises the CDC.