Vol. 7, Issue 1, Part A (2025)

Background: Allergic rhinitis is a chronic inflammatory disease of the upper respiratory tract mediated by IgE, characterized by increased levels of pro-inflammatory cytokines such as interleukin-6 (IL-6) and interleukin-8 (IL-8), which contribute to symptom severity and mucosal inflammation. Quercetin is a natural flavonoid known for its anti-inflammatory and immunomodulatory properties through various molecular pathways. Therefore, quercetin is considered a promising adjuvant therapy in the management of allergic rhinitis.
Methods: A systematic literature search was conducted using PubMed, Science Direct, and Google scholar data bases for studies published between 2014 and 2025 investigating the effect of quercetin on IL-6 and/or IL-8 levels and clinical symptoms of allergic rhinitis. Eligible studies included in vivo and in vitro research on animal models, as well as relevant narrative reviews. Studies were appraised based on study design, population, intervention, main outcomes, and methodological quality using the Newcastle-Ottawa Scale (NOS) or the Cochrane Risk of Bias Tool.
Results: Five studies met the inclusion criteria, including four experimental in vivo studies on BALB/c or Wistar mice and one narrative review. Most studies reported a significant reduction in IL-6 levels following quercetin administration; two studies also demonstrated reduced IL-8 levels. Additionally, quercetin improved allergic rhinitis symptoms such as sneezing, mucosal inflammation, and IgE levels. The proposed mechanisms included inhibition of the NF-κB and MAPK signaling pathways, along with increased IL-10 and FOXP3 expression. Most studies showed high methodological quality (NOS 8/9, Cochrane 7/8).
Conclusion: Quercetin shows potential as an adjuvant therapy for allergic rhinitis by modulating IL-6 and IL-8 expression and improving mucosal immune responses. However, further large-scale randomized controlled trials are needed to evaluate its clinical efficacy, safety, and optimal dosage in humans.