Background: Resveratrol is a natural, nonflavonoid polyphenol, exerting anti-inflammatory activity. It has been reported that resveratrol, together with carboxymethyl-β-glucan, can reduce nasal symptoms in children with allergic rhinitis (AR). In this study, the effect of resveratrol on nasal symptoms in adults with AR was investigated. Methods: We conducted a placebo-controlled, double-blinded study. One hundred and fifty-one adults (aged 18–60 years) with severe persistent AR were divided into a placebo-treated group (n = 50), a positive control budesonide-treated group (n = 50), and a resveratrol-treated group (n = 51). They were then treated with 2 sprays (100 µL/spray) in each nostril 3 times/day for 1 month. Nasal symptoms including obstruction, itching, sneezing, and rhinorrhea, and the levels of IgE, IL-4, TNF-α, and eosinophils in the blood were assessed at baseline and after treatment. Results: Adults treated with resveratrol or budesonide achieved a significant reduction in nasal symptoms compared to the placebo-treated group. The resveratrol treatment significantly decreased the IgE, IL-4, TNF-α, and eosinophil levels in the blood. In addition, the resveratrol treatment was found to improve the quality of life of adults with AR. Conclusion: Our preliminary study showed that intranasal resveratrol is capable of significantly improving nasal symptoms in adults with AR.