The role of

Introduction: Chronic rhinosinusitis (CRS) is a prevalent inflammatory disease of the upper airways, frequently characterized by recurrence and impaired quality of life. Persistent inflammation and bacterial biofilms contribute to disease chronicity. Topical plant-derived therapies may offer a preventive strategy in long-term CRS management. This study evaluated the effectiveness of a Pistacia lentiscus-based nasal medical device in reducing the impact of CRS recurrence on patients' daily life. Methods: In this retrospective, observational, single- center case-control study, 100 adult patients with chronic rhinosinusitis (CRS) and recurrent disease were identified and included from clinical records. Patients were stratified according to prior exposure to nasal drops containing ultra-fractionated Pistacia lentiscus oil in addition to isotonic saline nasal irrigation, or to isotonic saline nasal irrigation alone, according to routine clinical practice. All patients had undergone a 12-month follow-up regimen with assessments available at baseline, 30 days, and 12 months. The primary outcome was symptom severity measured using the Sino-Nasal Outcome Test (SNOT-22). Secondary outcomes included nasal cytology parameters, biofilm presence, nasal discharge, bacterial elements, supranuclear stria, and ciliary motility. Results: Of the 100 identified subjects, 92 were included in the final analysis due to loss to follow-up. In the exposed group, SNOT-22 scores showed a 40.6% reduction after the first month, compared with a 7.8% reduction observed in the control group ( Discussion: Overall, within the limits of this retrospective case-control design, patients exposed to Pistacia lentiscus oil in addition to standard saline irrigation showed greater improvement in patient-reported symptoms and selected cytological markers compared with patients treated with saline irrigation alone.