Nasal irrigation techniques have been used for many years and been shown to improve symptoms of rhinosinusitis. Although there is a wealth of literature available, establishing treatment protocols can be difficult because of the great variability in recommended composition (seawater or hypertonic or isotonic saline with or without additives) and irrigation technique (variations in pressure and volume). Nasal irrigation is also used in many centers as part of postoperative treatment protocols and in particular has been recommended following endoscopic sinus surgery (ESS). Nasal crusting and thick nasal discharge have a negative impact on these patients quality of life (QOL). At the time of our study, there are no studies comparing irrigation with mucolysis with saline irrigation following ESS. The investigators aimed to assess whether mucolysis is effective at improving patients QOL and reducing postoperative signs as assessed endoscopically.

The study will take place at Tel Aviv Sourasky medical center, otolaryngology outpatient clinic, a tertiary care academic hospital, for two years. It will be double-arm, open label, randomized controlled trial comparing two different methods of medical therapy following ESS. The allocation ratio is intended to be approximately equal for each arm. The two arms consisted of: a control arm (group A) of generic saline irrigation alone, irrigating with 20 mL per nostril tid for a total of 120 mL daily irrigation; and intervention arm (group B), which included generic N-Acetylcystine of 200 mg dissolved in 200 mL saline irrigated as per group A, 20 mL per nostril given tid daily (for a total of 120 mg). All medications will be used daily for the 3 months duration of the post-operative follow up. Patients will be instructed as to correct irrigation technique prior to discharge home from the hospital, and will be reminded of this technique at each postoperative clinic visit.

Inclusion Criteria:

1. Aged 18 or over
2. Patient undergoing endoscopic sinus surgery

Exclusion Criteria:

1. Allergy to N-Acetylcysteine,
2. Any other nasal surgery performed concomitantly
3. Diagnosed with inflammatory (e.g. Wegener's granulomatosis, sarcoidosis) nasal pathology
4. Diagnosed with systemic conditions affecting the nose e.g. Cystic fibrosis, Kartagener's syndrome
5. Unable to give informed consent due to mental impairment
6. Unable to adhere follow up or treatment.
7. Patients requiring any additional nasal sprays (e.g. steroid sprays)