Double-blinded randomized prospective trial of intranasal capsaicin treatment for nonallergic rhinitis

Nonallergic rhinitis (NAR) is currently a diagnosis of exclusion with an unclear pathophysiologic mechanism and limited treatment options. In patients diagnosed with NAR based on symptoms, negative skin testing and positive optical rhinometry (ORM), the study's objective was to evaluate the therapeutic action of intranasal capsaicin in the management of rhinitic symptoms and the effect on ORM readings.

Patients with a history of NAR underwent screening by a diagnostic intranasal capsaicin challenge with ORM and skin-prick testing. Twenty-two NAR patients were enrolled and randomized to either treatment with 0.1mM capsaicin (n = 11) or placebo (n = 11). Treatment consisted of 5 consecutive intranasal applications separated by 1 hour with follow-up at 4 and 12 weeks. At each visit, subjects underwent intranasal capsaicin challenge with ORM reading and a visual analog scale scoring of rhinitis symptoms.

Treatment with intranasal capsaicin resulted in a median change with improvement in total symptom score (TSS) of -5 from baseline vs an increase of 2 with placebo at 4 weeks, which remained significantly different between the groups at 12 weeks (p = 0.03). At 12 weeks posttreatment, 60% of the intervention group vs 80% of placebo-treated patients still met objective criteria for NAR by ORM.

Using ORM in the objective diagnosis of NAR, this trial showed that intranasal 0.1mM capsaicin not only improved rhinitic symptoms but also objectively reduced nasal reactivity and nasal congestion with a 40% responder rate at 12 weeks as noted by ORM.