That makes it easy for these particles to enter the nasal passages and trigger allergies. But people with allergies have a different reaction. In their case, the allergen triggers the release of histamine and other chemicals. The immune system misinterprets the pollen as an infection. To fight it off, the body responds with a runny nose, sneezing and watery eyes, in an effort to flush the irritants out.
Some people even get dark circles under their eyes caused by increased blood flow near the sinuses.
There isn't necessarily one thing that works, that is the best drug. It depends on what works best for you. New drugs are also in development that could help people who don't respond to currently available treatments. They could be on the market in the next five years. CNN Correspondent Rhonda Rowland contributed to this report.