Nonspecific nasal hyperreactivity (NHR) has been widespread observed in patients with allergic rhinitis (AR) and nonallergic rhinitis (NAR).As a clinical hallmark,NHR is more common in patients with NAR.The cold dry air (CDA) can stimulate nasal symptoms such as rhinorrhea and nasal obstruction,and the CDA provocation test can be used as a reliable objective method to evaluate NHR.The mechanism of CDA-induced nasal symptoms is very complicated and thus it has not yet been fully illuminated.The innervation of the nasal nerves includes sensory nerve (trigeminal ganglion),sympathetic nerve (superior cervical ganglion) and parasympathetic nerve (sphenopalatine ganglion).CDA innervation may also be associated with these nerves and associated signal pathway.Recently,general attention has been focused on the transient receptor potential (TRP) channel,including TRP vanilloid-1 (TRPV1) and TRP ankyrin-1 (TRPA1).More relevant researches are needed to further clarify the mechanism.