What are the Most Common Allergies?

Pollen 1 of 9

It seems people are allergic to just about everything these days. Learn which triggers are the most common causes of allergies so that you know what's making you sneeze!

It's estimated that as many as 20% of people are allergic to pollen, which makes it the most common allergen. This powdery substance is the cause of "hay fever", which occurs when wind carries pollen through the air for miles. This condition is most common in the fall, and the biggest offender is ragweed. A single ragweed plant can produce as much as a billion grains of pollen each season.