Plants produce tiny grains of pollen as part of their reproduction process. These powdery yellow grains are what fertilize other plants of the same species.1
Pollen can be spread from plant to plant by insects or birds, but often it is fine and light enough to be carried by the wind.2 It’s this airborne pollen — produced by certain types of trees, grasses, and weeds — that causes most seasonal allergy symptoms, also known as hay fever.1
If you have a pollen allergy, your body mistakes the pollen for a dangerous substance and triggers an immune response to fight it off. This involves the production of inflammatory substances in the body, including histamine, which cause your allergy symptoms.3
When there’s lots of pollen in the air, you’re more likely to inhale it and experience symptoms1, which is why your pollen allergies tend to be worse at certain times of year.