What Causes Fall Allergies?

Allergies plagues millions of Americans every fall.
What causes allergies?
Business Insider reports that fall allergies are often caused by weeds like ragweed.
Dust also causes allergies.
So does mold.
Fall allergy symptoms can include a runny nose, nasal congestion, sneezing, or itchy eyes.
Those suffering from allergies should start taking allergy medication at the beginning of September to alleviate symptoms before they start.