What are Seasonal Allergies?

Seasonal allergies, also known as allergic rhinitis or hay fever, are a type of allergic reaction that occurs at specific times of the year. They are caused when you breathe in tiny particles of pollen from trees, grass, and weeds that are released into the air. Your body makes antibodies to proteins on the pollen called antigens, causing an immune response. Antigens that cause an immune response are called allergens.  

Seasonal allergies can develop anytime during life. This is because the first time the immune system sees something, it’s considered priming, or primary exposure. During the primary exposure, the immune system learns how to respond and remember this.  Then when exposed to an allergen in the future, your immune cells will already have the instructions from your first exposure, which allows your immune response and therefore allergic reaction to be more powerful the second time you encounter an allergen. 

You may develop seasonal allergies because you moved to a new part of the country and are exposed to new allergens such as different kinds of pollen. People who already have allergies are at an increased risk of developing new allergies, including new seasonal allergies. Researchers are still trying to figure out why some people develop allergies and others do not.