This Is Why You Get Spring Allergies

Spring has sprung, which means the arrival of chirping birds, sunny days, blooming trees and flowers and … spring allergies.

But why do some people get allergies -- and all the miserable symptoms that accompany them -- while others don't? And what causes allergies, anyway?

"Allergy is actually a mistake that the immune system is making," says Dr. Calman Prussin, M.D., of the National Institute of Allergy and Infectious Diseases, in the video above. "Normally we make antibodies to fight germs and to recognize germs, and in this case, the immune system has made a mistake and instead is making an antibody that recognizes harmless things, such as pollens or animal dander."

For more on why we get spring allergies, watch the video above from the American Chemical Society.