Nasal carbon dioxide for the symptomatic treatment of perennial allergic rhinitis

Background: Brief nasal carbon dioxide insufflation has previously been shown to provide rapid relief of the symptoms of allergic rhinitis.

Objective: To examine the safety and efficacy of nasal carbon dioxide on the symptoms of perennial allergic rhinitis.

Methods: This was a randomized, double-blind, placebo-controlled, multicenter, in-clinic study that evaluated 2 flow rates (5 or 10 mL/s) and 2 administration durations (10 or 30 seconds per nostril) for nasal carbon dioxide vs placebo. Study participants rated their symptoms in clinic for 4 hours after administration and then through 24 hours outside the clinic. A total of 348 symptomatic patients with a minimum 2-year history of perennial allergic rhinitis requiring pharmacotherapy were randomized and treated.

Results: The mean change in total nasal symptom score from baseline at 30 minutes (the primary end point) showed greater improvement in the nasal carbon dioxide-treated groups compared with placebo. This change was statistically significant in the group treated with 10 mL/s for 10 seconds per nostril: -4.69 carbon dioxide vs -2.00 placebo (P = .03). The effect of a single dose lasted approximately 4 to 6 hours. The mean change from baseline at 30 minutes in total nonnasal symptom score was also statistically significant (-4.06 carbon dioxide vs -2.25 placebo, P = .029) for this group. The most common adverse events were nasal discomfort, lacrimation, and headache.

Conclusion: The study provides further evidence that nasal carbon dioxide is a potentially efficacious treatment for the symptoms of allergic rhinitis.