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Sometimes called hay fever, pollen allergy affects 10% of the U.S. population and is the most common allergy in the country. Hay fever, also known as allergic rhinitis, is an allergic response to pollen.
In people who are not allergic, the mucus in the nasal passages simply moves the pollen particles to the throat, where they are swallowed or coughed out. But something different happens in a person who is sensitive to pollen or other airborne allergens. In sensitive people, as soon as the pollen lands on the lining inside the nose, a chain reaction occurs where the mast cells in these tissues release histamine and other chemicals. The powerful chemicals contract certain cells that line some small blood vessels in the nose. This allows fluids to escape, which causes the nasal passages to swell, resulting in nasal congestion. Histamine also can cause sneezing, itching, irritation, and excess mucus production, which can result in allergic rhinitis.
Typical symptoms of pollen allergy include:
Sneezing, often with a runny or clogged nose
Cough and postnasal drip
Itching eyes, nose, and throat
Watering eyes
Conjunctivitis (inflammation of the lining of the eyelid)
Sinus congestion
Allergic shiners (dark circles under the eyes caused by increased blood flow near the sinuses)
Allergic salute (in a child, persistent upward rubbing of the nose that causes a crease mark on the nose)
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