(WGN Radio) – Feeling a little gross after the holidays? You may have one (or two, or three) of the overlapping symptoms of RSV, flu, COVID and strep.

We asked Dr. Sindhu Aderson at Northwestern Medicine to run through some of the most common symptoms and treatments for each virus and bacteria, to break down the differences.

With strep, the most common signs are sore throat and fevers, but not often a cough, Aderson said.

When it comes to flu, you’re more likely to see body aches. With COVID, one distinguishing symptom Aderson sees is fatigue, and occasionally loss of taste and/or smell.

With RSV, you’ll often hear wheezing and coughing as the main symptom. However, coughing is reported with all three of the viral illnesses (COVID, RSV and flu). It’s less common with strep, which is caused by a bacteria, Aderson said.

Trouble breathing is most common with COVID and RSV, but it can also be seen with patients with the flu, especially for people who are immunocompromised or elderly.

Fevers are possible across the board.

To easily compare symptoms between the four sicknesses, we created a chart you can use here.

Hear more from the interview with Dr. Aderson using the audio player below.

Those wishing for a definitive diagnosis can use a COVID test at home, or get tested for flu, RSV and strep at a doctor’s office.

“All of these illnesses and viruses tend to have a lot of shared symptoms,” Aderson said. “It’s difficult to tell, really narrow it down, unless we do that testing.”

Understanding what you have is important because the correct diagnosis can help doctors determine the correct treatment. There are antiviral medications available for both flu and COVID that, when taken early on, can keep things from getting worse.