We’re entering the fall and winter season, and with the cooler weather and more time spent indoors comes an increased risk for upper respiratory infections. So, if you feel a ticklish throat or runny nose coming on, here’s how to know what that could signal.

According to USA Today, it’s hard to know which virus you’ve come down with since many of the symptoms such as fever, runny nose, sore throat, coughing and general fatigue overlap. But there are key differences. For example, it’s unusual to have difficulty breathing with a cold or flu, but this could be a sign of COVID-19.

Loss of taste or smell is also a common symptom of COVID-19 but rarely present with the flu, cold or RSV. Other symptoms of influenza include a runny or stuffy nose, while respiratory syncytial virus (RSV) often causes a decrease in appetite and wheezing. The National Foundation of Infectious Diseases has a handy chart that helps delineate the main characteristics of each respiratory disease.

Timothy Brewer, a professor of medicine and epidemiology at the University of California Los Angeles explains that respiratory virus season typically starts in September and lasts until April. He says it is not the cold weather that makes us sick, but the colder temperatures do create an environment that makes it easy for all these viruses to survive and spread. 

Brewer adds that the single most important factor causing many of us to become ill with viral diseases during the winter months is “we just spend more time indoors.” He adds that while many people can recuperate at home and don’t have to know exactly what virus they are battling, testing can be important.

“It may not be important for you to know, but you might want to let your grandmother know if you were with your grandmother the last few days before you got sick,” he tells USA Today. “It might be useful information for some of your family or other individuals you are around just to let them know.”

There are several things you can do to stay healthy this season, says Brewer. These measures can protect you from getting infected by one or another virus. Keep washing your hands, social distancing and wearing masks indoors.

“The single most important things are stay home when you are sick and be up to date on your vaccinations,” he said.