Evaluation of the clinical efficacy and safety of grapeseed extract in the treatment of fall seasonal allergic rhinitis: a pilot study

Background: Herbal products are widely used by consumers as alternatives to prescription drugs in treating symptoms of allergic rhinitis. However, there have been few placebo-controlled clinical trials that have examined the efficacy or safety of these products. Although grapeseed extract (GSE) is an herbal that is marketed for treating allergic rhinitis, its efficacy is unproven. Objective: The aim of this study was to compare the efficacy and safety of GSE with placebo in the treatment of seasonal allergic rhinitis (SAR). Methods: This was a randomized, double-blind, placebo-controlled study of GSE 100 mg, twice daily, versus placebo. Patients with SAR and skin prick test sensitivity to ragweed were randomized to 8 weeks of active treatment or placebo which was begun before the ragweed pollen season. Outcomes included: daily symptom diary scores recorded by patients, rhinitis quality of life scores at baseline and after 4 and 8 weeks of treatment; and requirements for rescue chlorpheniramine. Safety was monitored with routine laboratory studies. Results: Over 8 weeks of treatment, no significant differences were observed between active and placebo groups in rhinitis quality of life assessments, symptom diary scores, or requirements for rescue antihistamine. No significant laboratory abnormalities were detected. Conclusions: This study did not show trends supporting the efficacy of GSE in the treatment of SAR.