Allergic rhinitis, also called hay fever or pollinosis, literally means "allergic nose inflammation," where rhino means "to do with the nose" and the ending -itis simply refers to inflammation.
Allergic rhinitis can either be seasonal or year-round. In most people, an allergen - something that triggers an allergy - sets their symptoms off at about the same time each year. Spring attacks are usually due to tree pollen, while grass pollens dominate in the summer and weed pollens in the autumn. Most people with allergic rhinitis are sensitive to more than one allergen.
Perennial allergic rhinitis appears year-round. This condition is most common in people with allergies to allergens that are present all year. Naturally, people who are allergic to house dust mites or to their own pets tend to suffer no matter the season. Allergic rhinitis affects about 20% of Canadians.