Allergic rhinitis is an allergic reaction of the lining of the nose. Seasonal allergic rhinitis is also called hay fever. 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.
Others are present year-round for example, the mites in house dust. When the lining tissues of the nose and sinuses come into contact with allergens, a chemical called histamine is released from cells in these tissues. Histamine causes the nose lining to swell, itch, and produce excess mucus. Common symptoms of allergic rhinitis are itchy, runny nose sneezing nasal and head congestion. Other possible symptoms include itchy, watery eyes itchy throat postnasal drainage.