The most common kind of allergy is allergic rhinitis; an allergy where most of symptoms of inflammation occur in the nose and the eyes and are caused by airborne allergens. Every year approximately one in ten people in Ireland experience the discomfort of allergic rhinitis.

Some people only have symptoms at certain times of the year, called seasonal allergic rhinitis (or "hay fever"), while others have symptoms all year round, called perennial allergic rhinitis.