In recent years, a number of randomized controlled trials have confirmed the efficacy and safety of acupuncture in the treatment of allergic rhinitis (AR). Indeed, the latest American clinical guidelines recommended acupuncture treatment for AR patients who are interested in non-pharmacological treatment. In conventional acupuncture treatment for AR, needles are inserted at specific acupoints in the body; with several studies demonstrating acupuncture of sphenopalatine ganglion (SPG) to improve nasal symptoms and quality of life in nasal inflammatory diseases. The investigators hypothesize that, compared with sham acupuncture and rescue medication (RM), active SPG acupuncture combined with RM would lead to greater improvements in symptoms score and reduction in overall need for antihistamines. To test this hypothesis the investigators design a randomized, double blind, controlled trial to evaluate the efficacy of SPG acupuncture in perennial AR patients (allergic to indoor allergens, including house dust mite, fungi, animal dander and so one) and to explore the potential underlying mechanisms.