Efficacy and immunomodulatory effects of licorice nasal spray in allergic rhinitis: A clinical study comparing with conventional steroid treatment

BACKGROUND: Licorice (Glycyrrhiza glabra) is recognized for its anti-inflammatory and immune-regulating properties. It has demonstrated potential in managing inflammation associated with various respiratory and inflammatory disorders. This study aimed to evaluate the effectiveness and safety of a licorice nasal spray (LNS) compared to a conventional steroid nasal spray (SNS) in treating allergic rhinitis. METHODS: In a randomized clinical trial, 60 patients with allergic rhinitis were assigned to either LNS or SNS groups. The SNS group received mometasone furoate nasal spray (Nasonex®) administered as one spray per nostril twice daily (total daily dose 200 μg), while the LNS group received licorice nasal spray using the same dosing schedule. Both groups were treated twice daily for one month. Outcomes were assessed through symptom scores (TNSS, SNOT-22), Visual Analog Scale (VAS) for various symptoms, acoustic rhinometry, endoscopy, mucociliary transport time (MCTT), and cytokine levels in nasal secretions. RESULTS: Both LNS and SNS significantly reduced nasal blockage and postnasal drip. In addition, LNS was associated with improvements in rhinorrhea, itchy nose, and sleep quality. LNS was associated with significant reductions in IL-4, IL-6, IL-10, TNF-α, and IFN-γ in nasal secretions, whereas changes in SNS were observed in a more limited subset of cytokines. Additionally, LNS improved MCTT, indicating enhanced mucociliary function. CONCLUSION: Licorice nasal spray effectively reduces allergic rhinitis symptoms and demonstrates a meaningful immunomodulatory effect comparable to steroid nasal spray. These results indicate that LNS may be a promising alternative therapy for patients with allergic rhinitis. TRIAL REGISTRATION: This study is prospectively registered with ISRCTN under the identifier ISRCTN13188211. Registration was completed on 01/09/2022, ensuring transparency and adherence to clinical trial reporting standards. Full trial details are accessible at https://www.isrctn.com/ISRCTN13188211.