It’s not always easy to know when you’ve got a seasonal allergy and when you’re suffering from a cold.

“Seasonal allergies are just that, seasonal,” according to Mark Moss, MD, an allergist with the University of Wisconsin School of Medicine. So if you can count on your symptoms appearing in spring, summer or fall, it’s an allergy.

Colds are far more common. Americans come down with an average of 2 to 4 colds a year, mostly in the winter months. In fact, colds account for more visits to the doctor than any other condition, according to the American Lung Association.

But allergies are on the rise. “The reason people are getting more allergies seems to revolve around our living in cleaner environments and having less exposure to bacteria than we would have found on farms that people grew up on 100 years ago almost exclusively,” said Moss.

Another difference? Colds are caused by a virus and usually run their course in a week. Allergies, on the other hand, result when your immune system overreacts to normally harmless substances like pollen and pet dander, and the symptoms can last for months.

Unlike colds, if you have seasonal allergies, at least one of your parents does, too, because the tendency to have allergies runs in the family.