Allergic Rhinitis (Hay Fever) Release of pollens   Allergic rhinitis is the single most common chronic disease experienced by human beings. In many developed countries, around 15-20% of the population has allergic rhinitis. Around 1 out of every 40 doctor office visits (1.5%) are due to allergic rhinitis.   Allergic rhinitis is caused by exposure to airborne allergens in the nose, such as dust mite feces, pollen grains, cockroach excrement, and animal dander. These allergens are trapped by the hairs and mucus in the nose. The allergens release soluble proteins that reach the mucous membranes of the nose, causing allergic rhinitis.   The most common features of allergic rhinitis include:   Sneezing attacks   Itching of the nose, eyes, pharynx and palate   Runny nose or congestion of the nose   With severe allergic rhinitis, the swelling of the lining of the nose may be associated with other symptoms, such as headaches, a loss of smell, and impaired taste. Perennial rhinitis is often associated with asthma. A blocked nose may lead to constant mouth-breathing, which can disturb breathing and worsen asthma. Poor sleep may impair daytime performance. Hay fever Hay fever refers to the seasonal allergic response to pollen, usually grass, but also some weeds and tree pollens. Allergic response to pollens often occurs in the nose (rhinitis) and the eyes (conjunctivitis), and less commonly in the lower airways (asthma). The symptoms of hay fever include nasal itching, frequent sneezing, runny or blocked nose, itchy / watery / red eyes. Some people may also experience an itchy throat and roof of the mouth, an itchy sensation inside the ears, and sometimes a skin rash on contact with plants (such as grass). The tendency to develop asthma from hay fever depends on the level of the pollen count and the size of pollen. Smaller pollens (such as birch pollen) cause more asthma since more pollen grains are inhaled into the lower airways than larger pollens. Since hay fever can have serious effects on sleep patterns, the ability to concentrate and on work efficiency, it may lead to poor performance at work and at school for sufferers.