Upper Airway Cough Syndrome

Upper airway cough syndrome (UACS), previously known as postnasal drip, describes chronic cough that occurs due to nasal and sinus conditions and is one of the most common causes of chronic cough.

UACS usually results from nasal and sinus conditions, including allergic rhinitis, nonallergic rhinitis, sinusitis, and environmental irritants.  Patients typically have:

• Chronic cough (>8 weeks)
• Nasal congestion and/or rhinorrhea
• Temporary improvement of the cough with nose-blowing or sneezing
• Worsening of the cough with exacerbation of the underlying condition (eg, periods of high pollen count in patients with allergic rhinitis)

The cough of UACS was previously thought to be due to the production of excessive mucus that accumulates in the throat and triggers a cough to clear these secretions.  As a result, symptoms thought to reflect UACS have included frequent throat clearing, persistent nasal discharge, and a liquid sensation flowing into the back of the throat.  However, it is likely that the underlying rhinologic condition that induces UACS triggers cough hypersensitivity (a neurogenic component) in which mechanical stimulation to the afferent limb of the cough reflex leads to excessive coughing.  This results in coughing out of proportion to secretion production.  For this reason, patients may have a predominantly dry (nonproductive) cough and may not present with excessive mucus.  Cobblestoning, a physical examination finding classically associated with UACS, is not sensitive.