Capnia conducted 5 randomized, controlled trials with approximately 1000 patients testing the safety and efficacy of nasal carbon dioxide in treating allergy symptoms (or allergic rhinitis). Four studies were completed in patients with seasonal allergic rhinitis and one in perennial allergic rhinitis.
These studies show significant effects in both seasonal and perennial allergic rhinitis, and on each of the individual nasal and non-nasal symptoms, with as little as 10 seconds of gas flow in each nostril. The magnitude of the effect appears to be substantially larger than reported effects of most antihistamines and in the range of that only seen with days of continuous dosing with intranasal corticosteroids. There have been no significant or long-lasting adverse events reported related to nasal carbon dioxide use or the device. Most common adverse events were generally administration-related (nasal discomfort and watery eyes) and stopped immediately when dosing stopped. Given its rapid effect and lack of significant side effects, Serenz is ideally suited for use on an as-needed only basis.
Casale TB, Romero FA, Spierings EL. Intranasal noninhaled carbon dioxide for the symptomatic treatment of seasonal allergic rhinitis. J Allergy Clin Immunol 2008 January;121(1):105-109.
Casale TB, Korenblat PE, Meltzer EO, Yen K, Bhatnagar A. Nasal carbon dioxide for the symptomatic treatment of perennial allergic rhinitis. Ann Allergy Asthma Immunol. 2011; 107(4):364-370.