Postnasal drip refers to the accumulation of mucus in the postnasal space, caused by hypersecretion from the paranasal sinuses or a disturbance of normal drainage. Postnasal drip may be the result of allergic rhinitis, acute or chronic sinusitis or anatomic obstructions.
Allergic rhinitis is common in both adults and children and often has a strong family history.
Prolonged or chronic sinusitis is usually associated with obstruction of drainage, but immunodeficiency and mucosal dysfunction should be considered. Nasal polyps are common in adults but extremely rare in children, except for those with cystic fibrosis. In children, enlarged adenoids are a common obstruction to sinus drainage and a reservoir of infection. Other causes of obstruction include septal deflections, congenital abnormalities, foreign bodies and impacted teeth. Exposure to industrial chemicals and cigarette smoke may also contribute to the development of postnasal drip.