Allergic rhinitis occurs when the nose and usually also the ears, eyes, sinuses, and throat come into contact with allergy-causing substances. The allergy-causing substances are called allergens. The most common allergens are pollens, molds, dust, and animal dander. Some allergens are present only during certain seasons, for example, ragweed in the fall. The allergic reaction they cause is called seasonal allergic rhinitis or hay fever. Other allergens are present year-round, such as the mites in house dust. These allergens cause a type of rhinitis called perennial allergic rhinitis.

Significant deviations from the normal range may require further evaluation by your physician.