Can you be allergic to mold? how do you know?

Yes you can: Mold spores are commonly found outdoors(though invisible) in the air, on warm , huid days. Symptoms can include runny or stuffy nose, post nasal drip or even coughing. See an allergist for simple testing to see if mold can be causing your symptoms. A full history and physical exam is needed to help make the diagnosis. There are very good treatments for this, too.