Do you know how to tell the difference between a cold and allergies?

It’s easy to get them confused. Just ask Paul Ehrlich, MD, a professor of pediatrics at New York University. He’d been an allergist for years when he came down with what he thought was a cold. “I’d had a watery, runny nose for several days when one of my patients took a look at me and said, ‘Oh, you have allergies, too!'” Ehrlich says.

He’d never had allergies before, but a checkup with another doctor confirmed that the patient was right. “Turns out I was allergic to birch trees, which were in bloom at the time,” he says.

A cold is an infection caused by a virus. Allergies are your immune system’s reaction to a substance like pollen or pet dander. Because the two conditions cause similar symptoms, like sniffles and stuffiness, many people get them mixed up. Knowing which is which can help you get the right treatment, and that will help you feel better faster.

It’s Probably Allergies If:

Clear or watery mucus. And it will stay clear, instead of becoming thick or discolored like it can with a cold.

Itchy or watery eyes. It’s rare to have itchy eyes when you have a cold.

Symptoms stay the same. Allergies may feel extra intense for the first day or 2, but you’ll have the same symptoms day after day.

Sniffles have lasted for more than a week. A cold usually clears up in 7 to 10 days, but allergies can last several weeks or longer.

Symptoms show up only in certain situations. Find yourself sneezing every spring or fall? Those are common times for allergies. Whereas colds and the flu usually show up in the late fall and winter. If being in a specific place makes you feel miserable (i.e. in a house with a cat), then you can bet you are having an allergic reaction.

It’s Probably a Cold If:

You have a cough, low fever, headache, or mild body aches. There are more than 200 cold viruses, and different viruses cause different symptoms. Even so, coughing, a fever, and achiness aren’t problems you usually see with allergies. The exception to the rule: Allergies can sometimes trigger a cough from post-nasal drip or if you have asthma.

Symptoms change every few days. You may start out with a fever and stuffy nose, then have a sore throat for a few days, or get a cough or sinus pain before getting better.

Yellow, green, or thick mucus. As immune cells fight back against the cold virus, they can make your mucus discolored or thick.