Allergic rhinitis represents a global health problem. Non-specific nasal hyperresponsiveness is an important feature of allergic and non-allergic rhinitis. This phenomenon is believed to result from the effect of allergic inflammation on the sensory nerves that supply the upper airway mucosa. A pharmacologic agent that has proved useful in the investigation of effects of neuronal stimulation is capsaicin, the pungent component of hot pepper. Intranasal capsaicin specifically stimulates afferent nerves consisting mostly of unmyelinated C fibers and some myelinated A-delta fibers. As a result it can trigger central and axonal reflexes, the latter being putatively mediated by the release of neuropeptides. Capsaicin as a blocking agent of neuropeptides, blocks the axon reflex and may exert a curative effect on allergic rhinitis.
Cheng, J., Yang, X. N., Liu, X., & Zhang, S. P. (2006). Capsaicin for allergic rhinitis in adults. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.cd004460.pub2