Safety and Tolerability of Shallot Oral Supplement in Patients with Allergic Rhinitis: A Randomized Pilot Clinical Trial

Abstract

            Shallot has long been suggested in Thai folk medicine to prevent allergic rhinitis (AR), but no scientific evidence on safety and tolerability is available to support the continuous use. The purpose of this study was to evaluate the adverse effects of the continuous use of oral shallot supplement in AR patients and determine the safety and tolerability by comparing the results with placebo. A prospective, randomized, double-blind, placebo-controlled, pilot study was performed in 50 AR patients. All patients received cetirizine 10 mg per day as standard treatment. An additional 3 g per day of either shallot capsules (equivalent to 1½ bulbs of fresh shallot) or placebo capsules were randomly prescribed for 4 weeks. Complete blood counts (CBC), blood urea nitrogen (BUN), serum creatinine (Cr), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) levels were evaluated before and after treatment. Vital signs and physical examination were performed before starting the study and repeated every 2 weeks thereafter. Assessment of adverse events and patient’s compliance were performed every 2 weeks. Patients’ satisfaction was assessed via visual analog scales in an exit interview. Twenty-five patients in the shallot group and 22 patients in the placebo group completed the study. No significant differences between groups were found in terms of body weight, blood pressure, heart rate, incidence of adverse events, compliance, serum levels of CBC, BUN, Cr, AST, and ALT, and patients’ satisfaction. In conclusion, the combination use of oral shallot supplement with cetirizine for 4 weeks is safe and well tolerated in AR patients.