出典:Wikipedia
出典:『Wikipedia』 (2011/08/03 01:12 UTC 版)
Post-nasal drip (PND), also known as Upper Airway Cough Syndrome (UACS), occurs when excessive mucus is produced by the nasal mucosa. The excess mucus accumulates in the throat or back of the nose. It can be caused by rhinitis (allergic or non-allergic), sinusitis (acute or chronic), laryngopharyngeal acid reflux (with or without heartburn), or by a disorder of swallowing (such as an esophageal motility disorder). It is frequently caused by allergies, which may be seasonal or persistent through the year. Birth control pills or pregnancy can also cause post-nasal drip because of the elevated levels of estrogen hormones.