The flu, a cold, allergies or COVID-19? How to decipher symptoms

Let’s say you have a runny nose, headache and cough. Are they signs of COVID-19 or just a run-of-the-mill common cold?  

Northwestern University epidemiologist Dr. Sadiya Khan breaks down the symptoms for COVID-19 and how they compare to typical seasonal viruses and allergies, while also stressing the importance of getting a flu vaccine this year — something the Centers for Disease Control and Prevention is recommending people do by October 31.

“By getting a flu vaccine, you not only protect yourself, you boost your own immune system and protect others from the flu as well as a more severe illness if you were to contract both influenza and COVID-19,” said Dr. Khan, assistant professor of medicine and epidemiology at Northwestern University Feinberg School of Medicine. “Getting vaccinated is especially important if you are pregnant or immunocompromised or have direct contact with someone who is.”

Unlike allergies, the common cold, flu and COVID-19 are caused by infectious viruses that are contagious, Khan said.

"There are many symptoms of a ‘common cold,’ flu and COVID-19 that overlap, including fever, sneezing, cough and fatigue,” Khan said. “One symptom that seems to be unique to COVID-19 is a loss of sense of smell or taste. However, none of these symptoms are perfect to diagnose the cause of ‘cold-like’ symptoms, and the only way to know for sure is to get tested.”

Allergies

"While seasonal allergies can also sometimes cause overlapping symptoms, they are not infectious or contagious and don’t cause a fever. It also is highly likely that people experiencing allergy symptoms are familiar with them, as they likely have the same symptoms every fall and spring." Common symptoms include:

• Runny or stuffy nose
• Sneezing
• Itchy/scratchy throat
• Itchy eyes and
• Postnasal drainage

Common cold

"The common cold is caused by many different respiratory viruses. Some of these can be dangerous in young children, such as respiratory syncytial virus, and lead to hospitalization, but often cause mild symptoms in older children or adults lasting about two to three days. In contrast to the flu and COVID-19, the common cold is usually a mild illness." Common symptoms include:

• Runny or stuffy nose
• Sneezing
• Sore throat
• Cough
• Sinus congestion and
• Postnasal drainage

The ‘flu’ 

“The ‘flu’ is caused by an influenza virus, which can cause mild to severe illness or even death." Common symptoms include:

• High fevers
• Sore throat
• Cough
• Shortness of breath or difficulty breathing
• Muscle aches or weakness
• Fatigue and
• Nausea, vomiting or diarrhea

COVID-19

“COVID-19 is caused by a new virus called SARS-CoV-2 and can be asymptomatic or cause mild to severe illness and has contributed to more than 200,000 United States deaths this year. The best way to protect yourself from COVID-19 is to wear a mask outside your home, practice physical distancing and wash hands frequently." Common symptoms include:

• High fevers
• Cough (it may be a deep cough)
• Shortness of breath or difficulty breathing
• Muscle aches or weakness
• Fatigue
• Nausea, vomiting or diarrhea
• Loss of taste and/or smell