Chronic rhinosinusitis is a common disease which causes persisting inflammatory conditions of one or more sinuses. This study was designed to evaluate the effect of thyme honey nasal spray as an adjunctive medication on chronic rhinosinusitis after functional endoscopic sinus surgery. This was a randomized, placebo controlled, double-blind clinical study. 64 patients with chronic rhinosinusitis undergoing functional endoscopic sinus surgery were enrolled in this study. Patients were randomized and blinded to receive either placebo or thyme honey nasal spray in addition to the standard regimen postoperatively. Patients were visited on postoperative days 7, 30 and 60. The sino-nasal outcome test, endoscopic grading system and sinus CT-scan were scored before operation and on the day 60 after surgery. 54 patients completed the study. Significant improvement was observed in both treatment groups. There were no significant changes in SNOT-22, endoscopy and CT-scan scores between the two study groups. However, a greater reduction in endoscopic scores was shown in thyme honey group. The incidence of adverse effects was not significantly different between the groups, but synechiae formation and epistaxis were lower in treatment group. Thyme honey nasal spray seems to be a low-priced potential adjuvant remedy with excellent safety profile, to reduce inflammation and polyp formation and also fostering mucosal healing for patients suffering from chronic rhinosinusitis. However, further studies are recommended.