Efficacy of Supportive Therapy of Allergic Rhinitis by Stinging Nettle (Urtica dioica) root extract: a Randomized, Double-Blind, Placebo- Controlled, Clinical Trial

The aim of this study was to survey the exact benefit of this herb in the management of clinical and laboratory signs and symptoms of allergic rhinitis. In a randomized double blind clinical trial, 74 patients with the signs and symptoms of allergic rhinitis and a positive skin prick test were selected and randomly divided into 2 groups who were taken Urtica dioica 150-mg, Urtidin® F.C Tablet) or placebo for one month. Their signs and symptoms, eosinophil percentage on nasal smear, serum IgE, and interleukin IL-4, IL-5, interferon- γ) levels were recorded. Forty patients completed the trial. Based on the Sino- Nasal Outcome Test 22 SNOT-22), a significant improvement in clinical symptom severity was observed in both groups P < .001). Furthermore, a statistically significant reduction in mean nasal smear eosinophil count was observed after treatment with Nettle P < .01). However, the mean IgE and IL4 and IL5 levels in the study group before and after treatment with Nettle saw no significant changes P > .1). Intergroup pre- and post-treatment laboratory findings suggested that there was a significant difference in post-treatment changes of mean IFN γ levels between the study and placebo group P = 0.017). Although the current study showed certain positive effects of Nettle in the management of allergic rhinitis on controlling the symptoms based on the SNOT-22, similar effects were demonstrated by placebo as well. We believe that our limitations underscore the need for larger, longer term studies of Nettle for the treatment of allergic rhinitis.