Chronic sinonasal symptoms (CSNS), such as coughing, throat clearing, nasal obstruction, crusting, dryness and discharge are extremely common in the general population. Although the physical symptoms are readily apparent, the psychosocial impact is often overlooked. Depression, anxiety, fear of social interaction, impaired personal relationships and decreased performance at work have all been associated with CSNS, often leading to multiple, frequent visits to the patient's primary care physician. A variety of clinical studies have shown that health-related quality of life (HRQoL) is significantly impaired in people with CSNS, with depressive symptoms being particularly common. CSNS may be due, in part, to tenacious nasal and paranasal secretions. It is therefore conceivable that a mucolytic may thin these secretions and improve mucociliary clearance, thereby reducing CSNS. N-acetylcysteine (NAC) is the most widely used mucolytic agent, particularly in patients with cystic fibrosis (CF), and has been documented as the most effective of the mucokinetic agents. Our group wishes to examine the use of NAC as a treatment for CSNS by testing the hypothesis that oral NAC reduces symptoms of CSNS compared to placebo.